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THE WORLD’S FIRST AND ONLY
Water Gradient
Contact Lens
A fundamentally new approach led
to breakthrough technology,
ushering in a new era in comfort.
ALSO IN THIS ISSUE
■ The Effects of Friction and Lubricity on Comfort
■ Introducing Water Gradient Technology
■ Overcoming Contact Lens Compromise
Contact Lens Spectrum
6/13
A scientific breakthrough
10 years in the making.
A new lens has arrived that’s
going to change everything.
See product instructions for complete wear, care and safety information.
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Special Edition
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By Jason J. Nichols, OD, MPH, PhD, FAAO
By Jason J. Nichols, OD, MPH, PhD
Daily Disposable Prescribing
Finally Begins to Trend Up
Learn why so many practitioners now choose
daily disposables as their go-to lenses.
6 Research Review
Dealing With Discomfort
By Eric Papas, PhD, MCOptom, DipCL
By Caroline A. Blackie, OD, PhD, FAAO, Donald R. Korb,
OD,FAAO, and Kelly Nichols, OD, MPH, PhD, FAAO, Dipl PH
An in-depth look at the epidemiology, diagnosis and
treatment of contact lens-related dryness.
Close to the Edge: Oxygen at
the Lens Periphery
10 Prescribing for Presbyopia
By Thomas G. Quinn, OD, MS
Clinical Relevance of Contact Lens Lubricity
By Desmond Fonn, MOptom, FAAO
Using science to provide better comfort for CL wearers.
Daily Disposables: Problem
Solver for the Presbyope
11 Contact Lens Design &
Material
Measuring Friction and Lubricity
of Soft Contact Lenses: A Review
By Neil Pence, OD, FAAO
By Lakshman N. Subbaraman, PhD, BSOptom, MSc, FAAO
and Lyndon W. Jones, PhD, FCOptom, FAAO
Novel Water Gradient Lens
Material
12 Dry Eye Dx and Tx
By William Townsend, OD, FAAO
Introducing Water Gradient Technology
By Ralph Stone, PhD
Daily disposable contact lenses with water gradient
technology represent a new era in contact lens wear.
How Daily Disposable Lenses Can
Address Contact Lens Dryness
13 Contact Lens Care &
Compliance
By Susan J. Gromacki, OD, MS, FAAO
The Development of Dailies Total1
Water Gradient Contact Lenses
Compliance With Daily
Disposable Contact Lenses
By John Pruitt, PhD and Erich Bauman, OD, FAAO
53 Contact Lens Practice Pearls
Research led to a departure from using a single bulk
material for the whole lens.
46
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5 Editor’s Perspective
The Shifting Prescribing Paradigm
Comfort may be tied to friction and lubricity.
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D E P A R T M E N T S
F E A T U R E S
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By Jason Miller, OD, MBA, FAAO
Groundbreaking Technology Debuts in Daily
Disposable Market
Panelists discuss a unique new lens that has surprising
characteristics designed to defeat discomfort.
Setting the Stage for Daily
Disposable Contact Lenses
54 The Business of Contact
Lenses
By Gary Gerber, OD
Winning the Race
55 Pediatric and Teen CL Care
Contact Lens
By Christine W. Sindt, OD, FAAO
SPECTRUM
®
Why Daily Disposable Lenses
Make Sense for Children
56 Treatment Plan
By William L. Miller, OD, PhD, FAAO
Contact Lens Discomfort: Can
Past Workshops Provide Insight?
Contact Lens Spectrum
UNIQUE WATER GRADIENT
5/13
THIS IS WHY contact lenses have
reached a new era in comfort.
33%
>80%
>80%
WATER CONTENT (%)
DAILIES TOTAL1® Water Gradient Contact Lenses feature an
increase from 33% to over 80% water content from core to
surface* for the highest oxygen transmissibility, and lasting
lubricity for exceptional end-of-day comfort.1, 2, 3
The First And Only Water Gradient Contact Lens
9.2
9.2
>80%
33%
>80%
Contact Lens Cross-Section
OUT OF 10
OUT OF 10
END-OF-DAY
~100%
COMFORT
COMFORT
Enlarged Water Gradient
UNIQUE WATER GRADIENT
LASTING LUBRICITY
OUTSTANDING COMFORT
Features different surface
and core water contents,
optimizing both surface
and core properties2
Ultrasoft, hydrophilic surface
gel approaches 100% water
at the outermost surface for
exceptional lubricity4
Lasting lubricity for
exceptional comfort from
beginning to end of day3
Let your customers experience the DAILIES TOTAL1®
contact lens difference today.
100%
100%
50%
50%
0.0%
0.0%
100% 100%
100% 100%
Time of
Insertion
Time of
Insertion
Time of
Removal
Removal
Time
of
(average
14 hours)
(average 14 hours)
PERFORMANCE DRIVEN BY SCIENCE
TM
*In vitro measurement of unworn lenses.
1. Based on the ratio of lens oxygen transmissibilities among daily disposable contact lenses. Alcon data on file, 2010.
2. Based on critical coefficient of friction measured by inclined plate method; significance demonstrated at the 0.05 level. Alcon data on file, 2011.
3. In a randomized, subject-masked clinical study, n=40. Alcon data on file, 2011.
4. Angelini TE, Nixon RM, Dunn AC, et al. Viscoelasticity and mesh-size at the surface of hydrogels characterized with microrheology. ARVO 2013;E-abstract 500, B0137.
See product instructions for complete wear, care and safety information. © 2013 Novartis 04/13 DAL13097JAD
82410 DAL13097JAD CLS.indd 1
5/22/13 3:27 PM
Contact Lens
SPECTRUM
EDITOR-IN-CHIEF
Jason J. Nichols, OD, MPH, PhD, FAAO
2008-Present
CLINICAL FEATURES EDITOR
Edward S. Bennett, OD, MSEd, FAAO
2007-Present
MANAGING EDITOR
Lisa Starcher
(215) 367-2168 • [email protected]
ASSISTANT EDITOR
Andy Myer
SPECIAL PROJECTS
EDITORIAL DIRECTOR Angela Jackson
(215) 316-9113 • [email protected]
EDITOR/PROJECT MANAGER Leslie Goldberg
FOUNDING EDITOR
Neal J. Bailey, OD, PhD
1986-1987
EDITORS EMERITUS
Joseph T. Barr, OD, MS, FAAO
1987-2007
Carla J. Mack, OD, MBA, FAAO
2007-2008
COLUMNISTS
Online Photo Diagnosis
Mark André, FAAO
Patrick J. Caroline, FAAO
Gregory W. DeNaeyer, OD, FAAO
William Townsend, OD, FAAO
Research Review
Eric Papas, PhD, MCOptom, DipCL FAAO
Loretta B. Szczotka-Flynn, OD, PhD, MS, FAAO
®
CLS
on the web
Need More Information?
Go beyond the pages and visit us online.
Searchable Article Archives
This Month’s Features
Breaking News
Digital Supplements & Videos
Upcoming Events/Seminars
Annual Contact Lenses & Solutions Summary
Subscription Information
Online Photo Diagnosis
www.clspectrum.com
An interactive extension of the leading
clinical contact lens information source.
Refractive Focus
David W. Berntsen, OD, FAAO
Jason Marsack, PhD
KEEP UP WITH INDUSTRY NEWS
Prescribing for Presbyopia/Astigmatism
Timothy B. Edrington, OD, MS, FAAO
Craig W. Norman, FCLSA
Thomas G. Quinn, OD, MS, FAAO
between issues of Contact Lens
Spectrum by subscribing to our e-mail
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Visit www.cltoday.com or the CLS site
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GP Insights
Edward S. Bennett, OD, MSEd, FAAO
Gregory W. DeNaeyer, OD, FAAO
Contact Lens Design & Materials
Neil Pence, OD, FAAO
Ronald K. Watanabe, OD, FAAO
Dry Eye Dx and Tx
Amber Gaume Giannoni, OD, FAAO
Katherine M. Mastrota, MS, OD, FAAO
William Townsend, OD, FAAO
Contact Lens Care & Compliance
Susan J. Gromacki, OD, MS, FAAO
Michael A. Ward, MMSc, FAAO
Visit www.clspectrum.com for complimentary access to the
digital version of the 2013 Special Edition of Contact Lens Spectrum.
Contact Lens Practice Pearls
John Mark Jackson, OD, MS, FAAO
Jason R. Miller, OD, MBA, FAAO
Gregory J. Nixon, OD, FAAO
The Business of Contact Lenses
Gary Gerber, OD
Clarke D. Newman, OD, FAAO
GROUP PUBLISHER, OPTOMETRIC PUBLICATIONS
Roger Zimmer
(203) 846-2827 • [email protected]
PROMOTIONAL EVENTS MANAGER Michelle Kieffer
Pediatric and Teen CL Care
Mary Lou French, OD, MEd, FAAO
Christine W. Sindt, OD, FAAO
ADVERTISING SALES
Dawn Schaefer, Eastern Region
(267) 373-9798 • [email protected]
Treatment Plan
William Miller, OD, PhD, FAAO
Leo Semes, OD, FAAO
Scott Schmidt, Eastern Region
(610) 564-7237 • [email protected]
EDITORIAL, PRODUCTION, AND SALES OFFICES:
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323 Norristown Road, Suite 200
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Contact Lens Case Reports
Mark P. André, FAAO
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Home page: www.clspectrum.com
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Body stock only
Contact Lens Spectrum 13th SE
UNIQUE WATER GRADIENT
33%
>80%
THIS IS WHY lasting lubricity
means lasting comfort.
>80%
WATER CONTENT (%)
DAILIES TOTAL1® Water Gradient Contact Lenses maintain 100% of their
lubricity after a day of wear.1 And because lubricity is highly predictive of
contact lens comfort, lasting lubricity means lasting comfort.2, 3, 4
>80%
33%
>80%
Contact Lens Cross-Section
~100%
PERCENT OF LUBRICITY FACTOR
The First and Only Water Gradient Contact Lens
Enlarged Water Gradient
100%
50%
9.2
OUT OF 10
END-OF-DAY
COMFORT
0.0%
Prior to
Insertion
Time of
Removal
UNIQUE WATER GRADIENT
LASTING LUBRICITY
100% LUBRICITY MAINTAINED
Features different surface
and core water contents,
optimizing both surface
and core properties5
Ultrasoft, hydrophilic surface
gel approaches 100% water
at the outermost surface6
for exceptional lubricity
Lens maintains 100% of its
initial lubricity even after a
day of wear1
Let your patients experience the DAILIES TOTAL1® contact lens difference today.
100%
50%
0.0%
100%
Time of
Insertion
100%
Time of
Removal
(average 14 hours)
PERFORMANCE DRIVEN BY SCIENCE™
1. Alcon data on file, 2011.
2. Brennan N. Contact lens-based correlates of soft lens wearing comfort. Optom Vis Sci. 2009;86:E-abstract 90957.
3. Coles CML, Brennan NA. Coefficient of friction and soft contact lens comfort. American Academy of Optometry. 2012;E-abstract 125603.
4. Kern JR, Rappon JM, Bauman E, Vaughn B. Assessment of the relationship between contact lens coefficient of friction and subject lens comfort. ARVO 2013;E-abstract 494, B0131.
5. Thekveli S, Qiu Y, Kapoor Y, Kumi A, Liang W, Pruitt J. Structure-property relationship of delefilcon A lenses. Cont Lens Anterior Eye. 2012;35(suppl 1):e14.
6. Angelini TE, Nixon RM, Dunn AC, et al. Viscoelasticity and mesh-size at the surface of hydrogels characterized with microrheology. ARVO 2013;E-abstract 500, B0137.
See product instructions for complete wear, care, and safety information. © 2013 Novartis 6/13 DAL13224JAD
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editor’s perspective
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M P H ,
P H D ,
F A A O
Daily Disposable
Prescribing Finally
Begins to Trend Up
A
s noted in our annual report for 2012, published in the January 2013 edition of
Contact Lens Spectrum, the daily disposable segment of the contact lens market was
the segment of the contact lens market associated with the most growth for the
second year running. This is indeed exciting news, particularly as the United States
market has lagged behind other worldwide markets for many years in terms of daily
disposable prescribing trends. It seems that practitioners here are beginning to
embrace the notion that daily disposables are associated with the best comfort,
convenience and ocular health in terms of the individual contact lens-wearing
experience.
As you will note in this Special Edition of Contact Lens Spectrum, we are on the
verge of seeing an even greater revolution in the daily disposable segment of the
market. Innovation, rather than incremental advances in product development, is
what drives market-leading advances and adoption of new ideas and technologies.
As you will see in this issue of Contact Lens Spectrum, we are now seeing an entirely
new material technology being used in the daily disposable platform. It’s only to be
anticipated that new technologies such as this will further drive trends we observe
in clinical practice. We hope you enjoy this Special Edition on daily disposable
contact lenses and associated new material technologies as you consider adopting
new prescribing trends in your practice.
www.clspectrum.com
CONTACT LENS SPECTRUM/SPECIAL EDITION 2013 •
5
Research Review
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Close to the Edge: Oxygen
at the Lens Periphery
I
n the days before silicone hydrogel materials became available, contact lens practitioners spent a
great deal of time worrying about oxygen transmissibility (Dk/t). These concerns seem to have
faded into the background in
recent years, but should we forget
about the issue altogether? In a
silicone hydrogel world where
daily wear is the dominant
modality, and — apart from
blinking — there is no eye closure during lens wear, are there
still risks?
Measuring Dk/t:
Location Matters
Manufacturers specify the
Dk/t of their contact lens materials based on measurements taken
at the center of a representative
lens, usually a lens with a nominal
back vertex power of –3.00D. For
any prescribed lens, however, the
thickness profile can vary significantly from the center to the periphery, depending on the design
and the back vertex power. Even
for a –3.00D spherical lens, the
thickness can be 2 or 3 times
greater at some positions outside
the center.
Because the Dk/t of a lens is
governed by its thickness, we
need to pay closest attention to
the regions of the ocular surface
covered by the thickest portions
of the lens. For most modern
lenses with diameters of 13.5 mm
to 14.5 mm, the peripheral
6
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cornea and the limbus are likely
to be the main sites under threat.
Corneal Swelling
Response to Hypoxia
Perhaps the most commonly
studied response to ocular hypoxia is corneal swelling. Swelling is
less pronounced at the periphery
of the cornea than at the center
because anatomical factors progressively limit the extent to
which swelling can occur as we
approach the limbus. For this
reason, there is little value in
measuring the far periphery of
the cornea, but some studies have
examined slightly less extreme
locations.
One such investigation showed
that certain features of a hydrogel
lens, such as thickened toric stabilization zones, can limit oxygen
flow and cause regional and localized swelling under daily wear
conditions (Tyagi et al, 2010).
Another study, which may have
more general application, found
that after 3 hours of open eye
wear, spherical lenses with lower
oxygen transmissibility can produce significant peripheral
swelling (Morgan et al, 2010).
These researchers analyzed their
data to estimate the minimum
CONTACT LENS SPECTRUM/SPECIAL EDITION 2013
Dk/t needed to avoid peripheral
corneal swelling in daily wear.
They calculated a value of 33 x
10-9 (cm s-1)(mLO2 mL-1 mm
Hg) across the entire lens.
Because most practitioners do
not routinely use pachometry in
daily practice, corneal swelling is
not useful as a clinical indicator of
the oxygen supply to the corneolimbal region. The most easily
accessible alternative marker
is the behavior of the limbal
vasculature.
Hyperemia as an
Alternate Marker
Blood vessels throughout the
body respond to the level of oxygen in their local environment,
and those at the limbus are no
exception. In the short term,
reduced oxygen causes hyperemia, which is perceived as ocular
redness or limbal flush. Although
these changes are reversible, prolonged periods of hyperemia can
lead to vascularization of the peripheral cornea, which is a more
serious condition with the potential for permanent consequences.
One of the earliest observations made with what were then
experimental silicone hydrogel
lenses was that eyes remained
whiter-looking (Papas et al,
1997). Until then, we believed
that mechanical irritation from
the lens edge caused the redness
habitually associated with soft
lenses. Later experiments using
goggles filled with different gas
mixtures demonstrated that oxy-
www.clspectrum.com
gen is an important factor mediating these responses (Papas,
2003). In addition, a number of
studies have confirmed the value
of silicone hydrogels in avoiding
limbal redness (Du Toit et al,
2001; Dumbleton et al, 2001;
Maldonado-Codina et al, 2004;
Brennan et al, 2006; Dumbleton
et al, 2006).
From a clinical standpoint, the
amount of redness produced by a
contact lens is inversely related to
the oxygen transmissibility at its
periphery (Papas, 1998); however, the minimum transmissibility
required to prevent hyperemia
from occurring remains a subject
of active debate. Thus far, the
only work that has directly addressed this question suggested a
Dk/t in the lens periphery of
about 55 x 10-9 (cm s-1)(mLO2
mL-1 mm Hg) as a reasonable
minimum target for the open eye
(Papas, 1998). This research was
conducted more than 15 years
ago at a time when few silicone
hydrogel lenses were available, so
it is surprising that there has
been little activity to update this
value.
Silicone Hydrogel
and the Redness Response
Of some relevance is a study
that compared the limbal redness
responses of two silicone hydrogel
lenses with that of a conventional
hydrogel lens during daily wear
(Maldonado-Codina et al, 2004).
Although the silicone hydrogel
lenses were made from materials
of dissimilar oxygen permeability,
the results showed that, on average, they caused minimal amounts
of redness that were similar in
magnitude to the hyperemia observed in the non-lens-wearing
control subjects. Eyes wearing the
conventional hydrogel lenses were
significantly redder than those
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wearing either of the two silicone hydrogel lenses.
Although the researchers in
the 2004 study did not try to
determine a transmissibility
threshold for limbal redness,
their observations were subsequently interpreted as evidence
that the amount of oxygen
transmitted by the silicone hydrogel lens with the lower Dk/t
was sufficient to prevent a vascular response in the open eye
(Morgan et al, 2010). The
peripheral transmissibility
of this lens was 36 x 10-9
(cm s-1) (mLO2 mL1 mm Hg),
a value that potentially lowers
experience of all participants.
Second, the peripheral thickness measurement for the reference lens in the 2004 study was
made at a diameter of 8 mm.
Although this was appropriate in
the context of the study’s primary
aim, which was to examine
corneal swelling, it does not correspond to the area of the lens
that would influence vascular
changes at the limbus. Thus,
more data must be accumulated
to satisfactorily resolve the uncertainty surrounding these numbers.
Regardless of the precise
values, it seems clear the open eye
is not immune to the effects of
From a clinical standpoint, the amount
of redness produced by a contact lens
is inversely related to the oxygen
transmissibility at its periphery.
the transmissibility requirement
somewhat and is similar to the
value I mentioned earlier for
peripheral corneal swelling.
Consider These
Qualifying Issues
Before accepting this conclusion regarding minimum oxygen transmissibility, however,
we should consider two qualifying issues. First, this estimate of
oxygen transmissibility (Morgan
et al, 2010) was made some
years after the original clinical
observations (MaldonadoCodina et al, 2004) by measuring a lens with a power of
–3.00D. Lenses in the study
ranged from –1.00D to –4.00D,
so the single value would not
have equally represented the
hypoxia that may occur from a
contact lens that has poor
oxygen-transmitting properties.
Fortunately, clinicians can avoid
this problem by choosing carefully from the array of contemporary lenses that are available. CLS
For references, please visit
www.clspectrum.com/references.asp
and click on document SE2013.
Associate Professor Papas is executive director
of Research & Development, Brien Holden Vision Institute and Vision Cooperative Research
Centre, and senior visiting fellow, School of
Optometry & Vision Science, University of New
South Wales, Sydney, Australia. The Brien
Holden Vision Institute and Vision Cooperative
Research Centre have received research funds
from B+L, AMO, and Allergan and have proprietary interest in products from Alcon, CooperVision, and Carl Zeiss. You can reach him at
[email protected].
CONTACT LENS SPECTRUM/SPECIAL EDITION 2013 •
7
Prescribing for Presbyopia
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Daily Disposables: Problem
Solver for the Presbyope
D
daily disposable lenses may be ideal for adolescents and occasional contact lens wearers (Wagner et al, 2011; Efron et al, 2012), but there’s
another population that’s ideal for daily dispos-
able wear: presbyopes. Though
well suited for occasional wear
due to specific lifestyle requests
(e.g. “I just want contact lenses
for social occasions and when I
work out”), presbyopes are great
daily disposable lens candidates
for other reasons.
Physiological Rationale
It has been well established that
contact lens-related dryness is
often a partner on the path to
presbyopia (Moss et al, 2008).
Meibomian gland dysfunction
(MGD), which becomes more
prevalent as we age (Hom et al,
1990), has been found to be associated with contact lens-related dryness (Young et al, 2012). MGD
reduces the lipids available to the
tear film, promoting more rapid
tear break-up, and resulting in a
relatively drier lens surface that
accumulates deposits more quickly.
This surface spoilage leads to
reduced contact lens comfort,
episodes of “foggy” vision, and
ultimately contact lens dropout.
In Control
Presbyopes may lack ocular
vigor, but many have financial
independence. When presented
with the indisputable case of how
10
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daily disposable lenses can improve their quality of life, many
presbyopes decide on the spot to
go with your recommendation.
Money Talks
When discussing the cost of
contact lenses, we break out
material fees from our service fee.
Material fees are set to be competitive with online contact lens
sources. When presenting material costs, be sure to factor in
manufacturer rebates, which can
be as much as $85 to $100.
Also remind patients that, with
daily disposable lenses, there’s no
need to buy contact lens care
solutions. This cost savings helps
offset the expense of materials.
A Little Philosophy
We believe daily disposable
lenses are a great option for virtually all contact lens wearers, so we
recommend daily disposable
lenses to most patients. We assess
a lower service fee to fit daily disposable lenses as opposed to what
we charge for 2-week or monthly
replacement lenses. We feel good
about this approach because:
1. It encourages patients to
choose the daily disposable option
2. Patient response to daily
CONTACT LENS SPECTRUM/SPECIAL EDITION 2013
disposable lenses is almost universally positive. As such, we generally spend less time managing
these patients.
3. When all is said and done,
we’re still making more profit
by prescribing daily disposable
lenses than we’d earn fitting
2-week or monthly lenses.
Make a Recommendation
The final key to success with
daily disposable lenses is to make
a firm recommendation for this
modality. If you believe, as I do,
that daily disposables are the way
to go for most patients, state that
with confidence. Most patients
appreciate clear guidance.
Everybody’s Happy
Daily disposable lenses provide
patients with a healthy option in
soft lens wear. When pursued,
your office benefits from happy
patients and higher profit margins.
When presented in the right
way, everybody wins with daily
disposables! CLS
For references, please visit
www.clspectrum.com/references.asp
and click on document SE2013.
Dr. Quinn is in group practice in Athens, Ohio.
He is an advisor to the GP Lens Institute and
an area manager for Vision Source. He is an
advisor or consultant to Alcon and B+L, has
received research funding from Alcon, AMO,
Allergan, and B+L, and has received lecture or
authorship honoraria from Alcon, B+L, CooperVision, GPLI, SynergEyes, and STAPLE program.
You can reach him at [email protected].
www.clspectrum.com
Contact Lens Design & Materials
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Novel Water
Gradient Lens Material
T
he introduction of a new daily disposable contact
lens may signal the need for a new category
of lens material. The Dailies Total1 contact lens
(Alcon), which was launched in various European
tant effect on handling, and lens fitting characteristics are properties
determined by the core of a contact
lens. With its 33 percent water content core, the Dailies Total1 lens
has the highest oxygen transmissibility of any daily disposable lens on
the market. It has a Dk of 140 and a
Dk/t of 156 for a –3.00D lens with
a center thickness of 0.09 mm.
Wettability, lubricity or low
coefficient of friction, the ability
to resist deposits or soiling and
overall biocompatibility with the
ocular surfaces are key characteristics of a contact lens surface. A
water content of over 80 percent
at the surface should result in a
wettable, lubricious lens.
Winning Combination
80
>
33
80
>
Figure 1. Schematic representation of Dailies Total1 water gradient contact lenses
markets during the past year, is
the first water gradient soft contact lens. What’s unique about
this lens is that the water content
is not constant throughout the
lens, but rather it changes from
the main body or core of the lens
to the surface. Here’s a brief
overview of the key characteristics of this material and the water
gradient phenomenon.
Novel Water Content Properties
Dailies Total1 lenses are manufactured from a new material,
delefilcon A, using a modification
of Alcon’s Lightstream Technol-
www.clspectrum.com
ogy, the manufacturing process
used to produce the Dailies Aqua
Comfort Plus daily disposable
contact lens. At the core of the
Dailies Total1 contact lens,
which comprises just over 90
percent of the lens, is a silicone
hydrogel material with a water
content of 33 percent. The surface of the lens is designed with a
water content of over 80 percent.
The change in water content
and lens structure occurs fairly
rapidly in the outer 5 percent of
the lens on both sides or surfaces.
Oxygen transmissibility, lens
modulus or stiffness and the resul-
With U.S. Food and Drug
Administration clearance already
secured, 2013 will see the introduction of Dailies Total1 lenses in the
United States. The advent of this
novel new contact lens material
with gradient water content properties and the benefits it may bring
will be eagerly awaited. The high
oxygen transmission of a silicone
hydrogel lens with the surface advantages of a high water content at
the surface should be a winning
combination for an ever-growing
number of patients wearing daily
disposable contact lenses. CLS
Dr. Pence is the associate dean for Clinical and
Patient Care Services, Indiana University School
of Optometry in Bloomington, Indiana. He has
received travel expenses, stipend, or reimbursement from Alcon and Bausch + Lomb.
You can reach him at [email protected].
CONTACT LENS SPECTRUM/SPECIAL EDITION 2013 •
11
Dry Eye Dx and Tx
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How Daily Disposable Lenses Can
Address Contact Lens Dryness
D
espite advances in soft contact lens materials,
design and surface characteristics and improvements in care solutions, discomfort and dryness
lead many patients to stop wearing their lenses.
What Studies Tell Us
In a multisite clinical study,
researchers investigated potential
causes for contact lens discontinuation (Young et al, 2002). They
found the majority of patients
who discontinued lens wear
(51 percent) did so because of
discomfort, and the most commonly reported type of discomfort was dryness (40 percent).
More recently, researchers
surveyed 4,207 contact lens
wearers to determine why they
stopped wearing their lenses
(Dumbleton et al, 2013). Forty
percent of the patients surveyed
had discontinued lens wear for
at least 4 months. The most
commonly reported reasons
for discontinuation were discomfort (24 percent) and dryness
(20 percent).
Dryness and Discomfort
Patients experiencing contact
lens dryness may report various
symptoms, such as discomfort,
irritation, burning, stinging,
foreign body sensation and visual
blurring (Sindt 2007), which may
be caused by poor prelens tear
stability, lens material or lens
deposits. Contaminants begin to
12
•
ing daily wear lenses exhibited
poor hand hygiene and inadequate lens and storage case
cleaning and had difficulty
remembering when to return for
aftercare.
Banish Deposits Daily
adhere to a lens surface within
minutes of application (Brennan
and Coles 2000), and the degree
and type of deposits are influenced by the water content, ionic
properties and silicone content
of a lens. Because lens deposits
decrease prelens tear film
breakup time, they may exacerbate the sensation of dryness
(Sindt 2007).
Lipids can significantly affect
contact lens wear, and our appreciation of their function and impact on the ocular surface and
contact lenses has expanded over
the last decade (Panaser and
Tighe 2012; Pucker and Nichols,
2012). For example, we have
learned a lipid coating increases
over time, and the aqueous tears
cannot form a stable layer over a
lipid-coated contact lens (Brennan and Coles, 2000).
Multipurpose contact lens
solutions are designed to remove
deposits, but they are never
100 percent successful in doing
so (Brennan and Coles, 2000).
In addition, improper lens care
may leave some deposits on the
lenses, leading to poor comfort
and vision. Wu et al (2010)
found that many patients wear-
CONTACT LENS SPECTRUM/SPECIAL EDITION 2013
How can we help patients
continue to wear their lenses
comfortably when they have
dryness or comfort issues? One
option is to prescribe daily
replacement lenses.
Daily disposable lenses may
reduce the risk of noncompliance
and complications associated
with surface deposits, thus
improving comfort and the total
lens-wearing experience for
patients.
Fahmy and colleagues (2010)
refitted symptomatic patients
who replaced their lenses at
intervals of 1 to 4 weeks into
Dailies AquaComfort Plus lenses.
At the end of 4 weeks, they found
statistically significant improvements in symptoms as well as in
limbal and bulbar redness and
conjunctival staining. CLS
For references, please visit
www.clspectrum.com/references.asp
and click on document SE2013.
Dr. Townsend practices in Canyon, Texas, and
is an adjunct professor at the University of
Houston College of Optometry. He is president
of the Ocular Surface Society of Optometry and
conducts research in ocular surface disease,
lens care solutions, and medications. He is also
an advisor to Alcon, B+L, CooperVision, Tearlab Corporation, and Vistakon. Contact him at
[email protected].
www.clspectrum.com
Contact Lens Care & Compliance
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Compliance With Daily
Disposable Contact Lenses
D
aily disposable contact lenses represent a growing segment of the soft lens market in the
United States, where they now comprise 17
percent of all fits and refits. Their usage is even
greater overseas, where they represent roughly 35 percent of contact lens sales in Europe and 55
percent in Asia (Nichols, 2012).
These statistics shouldn’t be
surprising, since daily disposables
offer convenience, particularly for
part-time wearers and people who
travel and they provide new-lens
comfort every day. In comparison
with frequent replacement
(2 weeks or more) daily disposable
lens wear has been shown to minimize lens deposition and tarsal abnormalities and provide better
subjective vision and overall satisfaction (Solomon et al 1996).
What’s more, daily disposable
lens wear eliminates the need for
care solutions and with them, the
possibility of preservative uptake
and release from lens care products. It also eliminates the need
for a lens storage case, a potential
source for contamination. Perhaps
the most important benefit of daily disposable contact lenses is the
elimination of concern regarding
compliance with lens care required with re-usable lenses.
Replacement Compliance
Many practitioners have difficulty monitoring how closely their
patients follow their lens wear and
www.clspectrum.com
replacement instructions. When
questioned, many patients, especially part-time lens wearers, have
difficulty remembering how frequently they replace their lenses.
A peer-reviewed paper by
Dumbleton et al (2010) presents
substantive data on compliance
rates with soft contact lens
replacement frequency. The
researchers analyzed responses
from 2,232 patients wearing silicone hydrogel and daily disposable lenses in North America.
They found that those who wear
daily disposable contact lenses
reported the highest rates of
compliance. In the United States,
patients wearing daily disposables
said they “always” replace their
lenses as recommended by the
manufacturer 82 percent of the
time, as compared with 34 percent
for 1-month lenses and 25 percent
for 2-week lenses. When factoring
out patients whose practitioners
instructed them to replace the
lenses less frequently than the
manufacturer recommends, the
compliance rates for lens replacement were 88 percent for daily
disposables, 73 percent for
monthly lenses and 48 percent for
biweekly lenses. What do these
numbers mean for our patients?
Good compliance means cleaner
lenses, which ultimately should
help reduce the incidence of many
contact lens-related complications. On the other hand, there
is more to compliance than just
replacement. For daily disposable
lenses, overnight wear and re-use
without disinfection are perhaps
of the greatest concern.
Complications Minimized
Chalmers and colleagues
(2010) reviewed the records of
1,276 soft lens wearers, representing 4,120 office visits and found
no significant correlation between
daily disposable lenses and inflammatory or infectious events. More
recently, in a carefully controlled
evaluation of 166 symptomatic
soft contact lens related corneal
infiltrative events, use of daily
disposable lenses was found to be
protective (over 12x) in comparison to reusable lenses (Chalmers
2012).
Although compliance alone will
never completely safeguard
patients from the potential of
complications, it is clearly a step
in the right direction. Daily disposable lens wear provides the
practitioner and patient with the
most compliant-friendly way to
wear contact lenses. CLS
For references, please visit
www.clspectrum.com/references.asp
and click on document SE2013.
Dr. Gromacki is a diplomate in the American
Academy of Optometry's Section on Cornea,
Contact Lenses and Refractive Technologies
and practices in Chevy Chase, Md.
CONTACT LENS SPECTRUM/SPECIAL EDITION 2013 •
13
DAILY DISPOSABLES
The Shifting
Prescribing Paradigm
Learn why so many practitioners now choose
daily disposables as their go-to lenses.
By Jason J. Nichols, OD, MPH, PhD
D
aily disposable contact
lenses have come a
long way since their introduction in the
1990s, owing to advances in material composition and
manufacturing processes. These lenses are recognized by patients and eyecare professionals not only
for their convenience but
also because they’re a
healthy option. The rising
appreciation of this modality is evidenced by increasing prescribing frequency
worldwide, even in the
United States, where practitioners have been slow to
embrace this modality. In
this article, I discuss the reasons why
daily disposable contact lenses are
challenging other modalities for the
top prescribing spot in many practices.
comfort, and 77 percent reported varying degrees of dryness.1 Non-lens wearers also reported significant increases in
late-day ocular discomfort, visual
changes, soreness and irritation. 1
What’s more, symptoms of ocular discomfort and dryness are the primary
reasons why patients become dissatis-
Daily disposable contact
lenses provide a fresh, clean
surface each day, and a clean
lens surface can be expected
to enhance comfort.
Dr. Nichols is the Kevin
Mc-Daid Vision Source
Professor at the University
of Houston College of
Optometry as well as the
editor-in-chief of Contact
Lens Spectrum and editor of
the weekly e-mail newsletter
Contact Lenses Today. He
has received research
funding or lecture honoraria
from Alcon Laboratories Inc.,
Bausch + Lomb and
Vistakon.
14
•
New-lens Comfort Every Day
Despite many years of research and implementation of various clinical management approaches and algorithms,
dryness and discomfort with contact
lens wear persist. In one study, 79 percent of lens wearers reported ocular dis-
CONTACT LENS SPECTRUM/SPECIAL EDITION 2013
fied and stop wearing their lenses. 2
Overall comfort and end-of-day comfort remain elusive goals.
Daily disposable contact lenses
provide a fresh, clean surface each
day, and a clean lens surface can be
expected to enhance comfort. When
compared with conventional and frequent replacement lenses (e.g.,
2-week, monthly), daily disposables
displayed less surface deposition and
better overall lens-wearing satisfaction.3
www.clspectrum.com
DAILY DISPOSABLES
Cost Effective for Part-time Wear
The cost of daily disposable contact lenses has been
considered a primary barrier to prescribing this
modality. In fact, a 2011 Quick Poll 4 by Contact
Lenses Today showed that cost is the number one
reason (58 percent) why eyecare practitioners don’t
prescribe daily disposables [Oct. 23, 2011]. A recent
study found that daily disposables can, indeed, be
cost-effective for part-time wearers.
Efron and colleagues examined the cost-per-wear
of daily, 2-week and monthly replacement lenses.5
They estimated the annual cost of professional fees,
care solutions and lenses and divided that sum by the
number of times the lenses are worn per year. They
assumed patients were fully compliant with their
wearing schedules and lens care and that they would
make the most cost-effective purchases of lenses and
care solutions. The study showed that the costper-wear of daily disposable spherical lenses is lower
than for reusable spherical lenses when worn from
1 to 4 days per week. At 5 days of lens wear per
week, the cost-per-wear is virtually the same for all
three spherical lens replacement frequencies, and at
6 or 7 days of lens wear per week, the cost-per-wear
of daily disposables is higher.
Although some lens wearers and practitioners may
perceive daily disposable lenses as more costly, this
study found that part-time wearers may receive the
additional benefit of a less expensive modality with
improved convenience. A 2012 Quick Poll4 by Contact Lenses Today showed that 76 percent of respondents believe daily disposable contact lenses are more
convenient than 2-week and monthly replacement
lenses [Nov. 11, 2012].
Improved Compliance, Fewer Complications
Eye health is of utmost importance to all of us,
which is yet another reason to consider prescribing
daily disposable lenses. In a 2010 Quick Poll4 by
Contact Lenses Today, 89 percent of respondents
believed the daily disposable modality is associated
with a general reduction in contact lens-associated
complications [Dec. 19, 2010]. Thus, the daily disposable modality may play an important role in promoting ocular health with contact lens wear, and
there may be several reasons for this.
In a recent Web-based survey, contact lens wearers
reported low compliance in hand-washing, lens-wearing times, rubbing and rinsing lenses, topping off solutions and lens case cleaning.7 None of the respondents
wearing planned replacement or daily wear soft lenses
or GP lenses reported total compliance; however,
8.9 percent of U.S. daily disposable lens wearers re-
www.clspectrum.com
Addresssing Allergy Symptoms
O
cular allergy symptoms can be especially
challenging for contact lens wearers, because
allergens and irritants can accumulate on lens
surfaces. Replacing lenses daily can help
improve comfort for allergy prone patients.3
A study by Solomon and colleagues found
that patients wearing daily disposable lenses
had decreased lens deposits and fewer associated tarsal abnormalities than those wearing
2-week replacement lenses.3 Another study
compared comfort and slit-lamp findings for
contact lens patients with ocular allergy symptoms. In this crossover study, patients wore
daily disposable lenses for 1 month and new
pairs of their habitual lenses (mostly 2-week
and monthly replacement modalities) for
1 month during allergy season.6 When comparing comfort, 67 percent of the patients reported better comfort with the daily disposable
lenses than with their habitual lenses; 18 percent reported improved comfort with a new
pair of their habitual lenses. Slit-lamp findings
of bulbar redness, corneal staining, palpebral
redness and lid roughness were improved with
the daily disposable lenses compared with new
habitual lenses.6 Some study participants reported they were able to reduce or discontinue
use of their allergy medications while wearing
daily disposable lenses.6
ported full compliance in all behaviors.
In another study, researchers found that practitioners were more compliant in prescribing the manufacturer’s recommended replacement schedule for
daily disposable lenses than for 2-week replacement
lenses.8 Similarly, patients were more likely to adhere
to the recommended replacement schedule for daily
disposable lenses than for 2-week replacement lenses. In other studies that compared patients wearing
daily disposables with those wearing conventional
daily lenses or frequent replacement lenses, those in
the daily disposable groups had lower complication
rates.3,9
Although one study10 found an increased risk of
CONTACT LENS SPECTRUM/SPECIAL EDITION 2013 •
15
DAILY DISPOSABLES
microbial keratitis with some daily disposable lenses
— a somewhat perplexing finding — a more recent
study found daily disposable wear to be highly protective against symptomatic corneal infiltrative
events.11 Although daily disposable lens wear still requires proper hand-washing and compliance with
daily replacement, this modality has eliminated the
need for cleaning, disinfecting and storing lenses.
Perhaps the removal of these steps has helped to improve compliance.
A Good Fit for Kids
Children can be successful contact lens wearers,12-14
and they report significantly higher satisfaction with
their quality of vision when wearing contact lenses as
opposed to eyeglasses during sports participation.15
Similarly, children who wear contact lenses report
significantly higher self-perception of their physical
appearance and social acceptance than those of the
same age who wear eyeglasses.16
Studies specifically examining daily disposable
lenses and children found high success rates.12-14 The
children in these studies demonstrated good vision,
good ocular health with no significant complications,
and excellent lens-handling skills. Most of the children and their parents reported high levels of satisfaction with contact lens wear. The majority of
wearers preferred contact lenses over spectacles for
vision, comfort and their appearance.12 In addition,
having a back-up supply of daily disposable lenses is
helpful for children, who may lose or damage their
lenses more often than adults.14
Because daily disposable lenses don’t require
cleaning and disinfecting, they may be of particular
benefit to children.14 While careful hand-washing
and diligent attention to prescribed wearing times
and follow-up visits remain important responsibilities for children and parents, daily disposable lenses
may provide a convenient and consistently clean option.
Prescribing Rates on the Rise
According to an international survey, daily disposable lenses, while not as widely prescribed as 1- and
4-week replacement lenses, have gained popularity in
the countries surveyed (Australia, Canada, Japan,
The Netherlands, Norway, the United Kingdom,
and the United States).17 Although they are especially
popular in Japan, Norway and the United Kingdom,
this survey found a significant increase in the prescribing rate for daily disposable lenses in the lesser
prescribing countries (Australia, Canada, The
16
•
CONTACT LENS SPECTRUM/SPECIAL EDITION 2013
Netherlands and the United States), especially in the
last 3 years of the survey (2006 to 2008). Also of note
in this survey, daily disposable lenses were worn
more often by men, part-time wearers and patients
who were slightly younger than those wearing
reusable soft lenses.
Newly released data from 40 countries during the
period 2007 to 2011 show daily disposable lenses are
gaining in popularity and now represent nearly
25 percent of the soft lenses prescribed in these
countries.18 According to this study, daily disposables
are most frequently prescribed in Japan and parts of
Recent data for the
United States indicate
that for the past few years,
daily disposable lenses
have enjoyed the highest
yearly percentage growth
rates of almost all
categories.
Northern Europe. According to these researchers,
cost appears to be the most significant factor in prescribing daily disposable lenses, and they found a relationship between a country’s gross domestic
product (basically, a measure of average wealth of individuals in a nation) and frequency of daily disposable fittings. In general, the countries with a higher
income were associated with more daily disposable
fittings. One notable exception was the U.S. market.
Although the United States was among the top five
countries for gross domestic product, it ranked 29th
out of 40 countries for proportion of daily disposable
fittings.18 Despite this puzzling finding, optimism for
the growth of daily disposable lenses remains high in
North America.
More recent data for the United States indicate
that for the past few years, daily disposable lenses
have enjoyed the highest yearly percentage growth
rates of almost all categories.19 Data from the Contact
Lens Spectrum Annual Report 2012 show that when
compared with other modalities, such as 2-week replacement or quarterly replacement lenses, the daily
disposable category showed substantial gains in 2012
www.clspectrum.com
DAILY DISPOSABLES
compared to 2011. Daily disposables were used in
about 17 percent of fits and refits for 2012, up from
14 percent in 2011 and 11 percent in 2009. Data
from GfK Retail and Technology showed the daily
disposable category grew by nearly 19 percent in the
The prescribing rates for
daily disposables are
trending upward, and
the benefits of daily
disposables make that an
easy trend to understand.
United States between January and September 2012
when compared with the same time period in 2011.19
Trend information for daily disposables for 2013
also appears positive. Data from a Contact Lens Spec-
trum survey regarding anticipated use for the coming
year reveals that 64 percent of respondents expect to
prescribe silicone hydrogel daily disposables, and 52
percent expect to prescribe hydrogel daily disposable
lenses more frequently in 2013.19
When comparing data from 2011 and 2012 for
Europe, Japan and the United States, daily disposables exhibited the highest growth rates in the U.S.
market.19
Finally, a 2012 Quick Poll4 by Contact Lenses
Today showed that 44 percent of respondents believe daily disposables will dominate the contact lens
market in the next few years [Oct. 28, 2012]. These
trends suggest that practitioners and patients are realizing the benefits of the daily disposable modality.
Understandable Trend
Daily disposable contact lenses are available with an
extensive array of vision-correcting capabilities in
numerous lens materials and a wide range of parameters. The prescribing rates for daily disposables are
trending upward, and the benefits of daily disposables make that an easy trend to understand. CLS
References
1. Begley CG, Chalmers RL, Mitchell GL, et al. Characterization of ocular surface symptoms from optometric practices in
North America. Cornea 2001;20: 610-618.
2. Richdale K, Sinnott LT, Skadahl E, Nichols JJ. Frequency of
and factors associated with contact lens dissatisfaction and
discontinuation. Cornea 2007;26:168-174.
3. Solomon OD, Freeman MI, Boshnick EL, et al. A 3-year
prospective study of the clinical performance of daily disposable contact lenses compared with frequent replacement and
conventional daily wear contact lenses. CLAO J 1996;22:250257.
4. Contact Lenses Today. http://www.cltoday.com/archive.asp
5. Efron N, Efron SE, Morgan PB, Morgan SL. A ‘cost-perwear’ model based on contact lens replacement frequency.
Clin Exp Optom 2010;93:253-260.
6. Hayes VY, Schnider CM, Veys J. An evaluation of 1-day disposable contact lens wear in a population of allergy sufferers.
Cont Lens Anterior Eye 2003;26:85-93.
7. Morgan PG, Efron N, Toshida H, Nichols JJ. An international
analysis of contact lens compliance. Cont Lens Anterior Eye
2011;34:223-228.
8. Dumbleton K, Richter D, Woods C, Jones L, Fonn D. Compliance with contact lens replacement in Canada and the
United States. Optom Vis Sci 2010;87:131-139.
9. Suchecki JK, Ehlers WH, Donshik PC. A comparison of contact lens-related complications in various daily wear modalities. CLAO J 2000;26:204-213.
10. Dart JK, Radford CF, Minassian D, Verma S, Stapleton F.
Risk factors for microbial keratitis with contemporary con-
www.clspectrum.com
tact lenses: a case-control study. Ophthalmology
2008;115(10):1647-1654.
11. Chalmers RL, Keay L, McNally J, Kern J. Multicenter casecontrol study of the role of lens materials and care products
on the development of corneal infiltrates. Optom Vis Sci
2012;89(3):316-325.
12. Li L, Moody K, Tan DT, Yew KC, Ming PY, Long QB.
Contact lenses in pediatrics study in Singapore. Eye Contact
Lens 2009;35:188-195.
13. Walline JJ, Jones LA, Rah MJ et al; CLIP Study Group. Contact Lenses in Pediatrics (CLIP) Study: chair time and ocular
health. Optom Vis Sci 2007;84:896-902.
14. Walline JJ, Long S, Zadnik K. Daily disposable contact lens
wear in myopic children. Optom Vis Sci 2004;81:255-259.
15. Rah MJ, Walline JJ, Jones-Jordan LA, et al. Vision specific
quality of life of pediatric contact lens wearers. Optom Vis Sci
2010;87:560-566.
16. Walline JJ, Jones LA, Sinnott L, et al; ACHIEVE Study
Group. Randomized trial of the effect of contact lens wear on
self-perception in children. Optom Vis Sci 2009;86:222-232.
17. Efron N, Morgan PB, Helland M, et al. Daily disposable
contact lens prescribing around the world. Cont Lens Anterior
Eye 2010;33:225-227.
18. Efron N, Morgan PB, Woods CA; The International Contact
Lens Prescribing Survey Consortium. An international
survey of daily disposable contact lens prescribing. Clin Exp
Optom 2013;96:58-64.
19. Nichols JJ. Contact Lenses 2012. Contact Lens Spectrum
2013;28(1):24-26, 28, 29, 52.
CONTACT LENS SPECTRUM/SPECIAL EDITION 2013 •
17
Contact Lens Spectrum
If your presbyopic patients aren’t experiencing
clear binocular vision, they may not be in
AIR OPTIX® AQUA Multifocal contact lenses.
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Are preferred by patients over other multifocal
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Important information for AIR OPTIX® AQUA Multifocal (lotrafilcon B) contact lenses: For daily wear or extended wear up to 6 nights for near/far-sightedness and/or presbyopia.
Risk of serious eye problems (i.e. corneal ulcer) is greater for extended wear. In rare cases, loss of vision may result. Side effects like discomfort, mild burning or stinging may occur.
References: 1. In a randomized, subject-masked clinical study at 20 sites with 252 patients; significance demonstrated at the 0.05 level; Alcon data on file, 2009. 2. Rappon J. Center-near multifocal
innovation: optical and material enhancements lead to more satisfied presbyopic patients. Optom Vis Sci. 2009;86:E-abstract 095557. 3. In a randomized, subject-masked clinical trial at 6 sites with
47 patients; significance demonstrated at the 0.05 level; Alcon data on file, 2008. 4. Based on a third-party industry report, 12 months ending October 2012; Alcon data on file.
See product instructions for complete wear, care and safety information.
© 2013 Novartis 12/12 AOM13003JAD
80980 AOM13003JAD CLS.indd 1
1/14/13 3:34 PM
CONTACT LENS COMFORT
Dealing With Discomfort
An in-depth look at the epidemiology, diagnosis and
treatment of contact lens-related dryness.
By Caroline A. Blackie, OD, PhD, FAAO, Donald R. Korb, OD,
FAAO, & Kelly Nichols, OD, MPH, PhD, FAAO, Dipl PH
Dr. Blackie is a charter
member of the Ocular Surface Society of Optometry.
She is the clinical research
scientist for TearScience
Inc. as well as for Korb &
Associates in Boston.
Dr. Korb is cofounder and
chief technical officer at
TearScience and cofounder
and director of research of
Korb & Associates. He has a
proprietary interest in Alcon.
Dr. Nichols is a professor
at the University of Houston
College of Optometry. She
has stock options in TearLab
and is a consultant/advisor
to Alcon, Allergan,
Bausch + Lomb and SarCode.
She has received research
support from Alcon Allergan,
SarCode, TearLab and
Vistakon.
www.clspectrum.com
D
espite years of research
and discovery, contact
lens-related discomfort
(CLD) remains highly
prevalent, with an estimated 50 percent of U.S. lens wearers
affected.1 Wearers frequently report
general symptoms of dryness and discomfort, as well as specific complaints, such as grittiness and
itchiness.2
A study involving patients in the
United States and Canada found that
79 percent of contact lens wearers reported discomfort, and 77 percent reported dryness. 3 Together these
symptoms represent the number one
reason why patients stop wearing
their contact lenses, which is particularly significant when we consider
that about 3.5 million people start
wearing contact lenses each year, but
approximately 2 to 3 million established lens wearers discontinue lens
wear each year.4
Recognizing symptoms is relatively
straightforward for clinicians, but
identifying signs can be challenging.
In a recent study, 23 percent of soft
lens wearers with self-reported dryness showed no signs upon clinical examination using various standard
tests.5 Furthermore, no single sign —
significant corneal staining or reduced
tear meniscus height, for example —
was present in the majority of lens
wearers.
This study supports the findings of
previous studies: Symptoms, even
when significant, frequently do not
correlate with ocular signs. Young
and colleagues 5 also reported that
some contact lens-related findings appear to be common among these patients, such as poor lens wetting, rapid
tear breakup times and higher levels
of deposits on lenses. They also found
that asymptomatic individuals consistently report longer average comfortable lens-wearing times and less
end-of-day discomfort. In contrast,
patients with dryness symptoms reported, on average, 3.9 to 4.3+ hours
of uncomfortable lens wear per day.
Epidemiology of CLD
Researchers have determined that
more women than men have CLD,6
but the reasons for the higher prevalence among women are not fully understood. Some have hypothesized
that hormones may play a role or that
women are more likely to report
symptoms.7
Studies reveal interesting information about age and contact lens wear.
Richdale and colleagues,2 who correlated contact lens dropout with ocular discomfort and dryness, found in
their study that older patients (by ap-
CONTACT LENS SPECTRUM/SPECIAL EDITION 2013 •
19
CONTACT LENS COMFORT
proximately 9.5 years) and those who had started
contact lens wear at a later age (approximately 4 to 5
years later) were more likely to stop wearing contact
lenses.
As we would expect, contact lens wearers bothered by symptoms will decrease wearing time and
eventually discontinue lens wear.5 In a cross-sectional
survey of 730 people, the permanent discontinuation
rate was 24 percent,2 and a more recent survey of
more than 4,000 Canadian patients found that about
23% of those surveyed had discontinued contact lens
wear permanently.8
In our experience, some patients who have
stopped wearing contact lenses, as well as some current lens wearers who have significant discomfort or
visual symptoms, feel their quality of life has decreased, because many appreciate the improved vision and self-perception of physical appearance while
wearing contact lenses.
Mechanisms Underlying
Contact Lens Discomfort
Over the past 10 years, numerous mechanisms
have been identified as key contributors to dryness in
contact lens wearers.
•Altered Tear Film: Wearing a contact lens can
produce a spectrum of ocular changes, including increased reflex tear secretion, deprivation of the wiping action of the lids over the covered ocular
surfaces, elevated tear osmolarity and increased mucus production by non-goblet cells in the tarsal conjunctiva.9 As first reported by Tomlinson,10 however,
the most important factor influencing discomfort
with contemporary contact lenses is increased evaporation from the lens and ocular surfaces.9,10 The importance of prelens humidity was clinically
demonstrated when 30 minutes of 100 percent humidity improved the prelens lipid layer thickness and
comfort of hydrogel lenses.9
•Lens Wettability: A key factor in the biocompatibility of a contact lens is the tear film’s ability to
adequately cover and maintain its integrity over the
lens surface. Unfortunately, the surface of a contact
lens lacks the mucus-attaching properties of the
cornea and the ocular surfaces and is not well
equipped to secure the foundational mucus layer(s)
essential for forming all layers of the tear film. Thus,
the tear film over the contact lens cannot duplicate
the characteristics of the tear film over the cornea.
With contact lens wear, the lipid layer is rarely
equivalent to the usual lipid layer of the tear film in
thickness or other characteristics.11 Therefore, the
rate of evaporation increases, tear film constituents
20
•
CONTACT LENS SPECTRUM/SPECIAL EDITION 2013
denature on the lens surface and, in combination
with the thinner pre- and postlens tear films, friction
between the cornea and the contact lens, and the lid
wiper and the contact lens is inevitable with resulting
discomfort.12
•Corneal Desiccation: Because contact lens wear
increases evaporation of the tear film, water is drawn
from the tear film, thinning the postlens tear film.
Consequently, the cornea may desiccate beneath a
thin, high water content lens, leading to corneal epithelial defects and generalized discomfort.13
•Lid Wiper Epitheliopathy (LWE): When associated with contact lens wear, LWE in otherwise
suitable contact lens wearers is most likely a result of
the altered characteristics of the tear film between
the lens and the lid wiper, compromising lubrication.
An inadequate lipid layer is believed to play a significant role. Without adequate lubrication, the anterior
surface of the contact lens is presented to the lid
wiper at a rate on average of 12 to 15 blinks per
minute,14 thousands of times a day. This activity can
cause physical trauma, mechanical abrasion and inflammation of the epithelial cells of the lid wiper, resulting in symptoms of discomfort. 12 Without an
adequate lubricating layer, the lid wiper becomes a
primary source of discomfort with contact lenses.
•Giant Papillary Conjunctivitis (GPC): With
the increased use of disposable contact lenses, particularly daily disposables, GPC is less of an issue today, but it still may occur. Generally, it is related to
the difficulty in keeping the lenses wet and clean.
With compromised wettability or a buildup of deposits, the friction/trauma applied by the lens to the
palpebral conjunctiva escalates, as does the likelihood
of GPC.
•Blinking: Blinking is critical for wetting the ocular and contact lens surfaces, maintaining the lipid
layer and minimizing evaporation, yet it is often
overlooked in the clinical examination of a patient
presenting with symptoms. Forceful blinking helps
increase the lipid layer thickness, presumably by augmenting the expression from the meibomian glands.9
Contact lens wear affects the blink rate and amplitude, frequently inhibiting proper blinking and further exacerbating the detrimental effects of the
contact lens on the tear film.9
•Meibomian Gland Dysfunction (MGD): The
blink is considered the primary mechanism for expressing oil from the glands, thus chronically reduced blink rate and amplitude, which are frequently
observed with contact lens wear, can result in a
reduced meibomian gland function and secretion
output within hours.15 MGD may lead to significant
www.clspectrum.com
CONTACT LENS COMFORT
symptoms of ocular discomfort with contact lens
wear.16-17 Reduced meibomian gland secretion contributes to contact lens discomfort, because evaporation from the tear film increases. This may initiate
the cascade of LWE, which may further inhibit
blinking. Similarly, if MGD develops during contact
lens wear, discomfort may develop.
Although the mechanisms involved in ocular dryness associated with contact lens wear are numerous
and complex, we know that MGD may well be the
leading cause of dry eye 18 and the most common
cause of contact lens intolerance.19 These facts play
an important role in diagnosing and managing CLD.
Diagnostic Aids
To appreciate the numerous tests required to
evaluate the ocular surface, we must understand the
effects of a contact lens on the eye. Even on a
healthy ocular surface and tear film, a contact lens
disrupts normal tear physiology through multiple
mechanisms. For example, it will:20
• Increase prelens tear film thinning and breakup
time
• Alter and thin the lipid layer
• Increase evaporation.
In addition, the edge of a contact lens introduces
physical and rheological challenges, including those
resulting from meniscus formation. The surface of a
contact lens and adherent material may also traumatize the ocular and conjunctival surfaces and present
immunological challenges.9 Thus, a thorough assessment of the patient’s symptom history, including
management successes and failures, as well as a complete evaluation of the ocular surface, the eyelids, the
blink and the interaction of the contact lens with the
tear film and ocular environment is important for
successful contact lens wear.
The following tests are often used in clinical practice:
•Questionnaires: The Contact Lens Dry Eye
Questionnaire,21 the Standard Patient Evaluation of
Eye Dryness (SPEED) questionnaire22 or other surveys that ask about frequency and intensity of symptoms and late-day dryness may reveal important
information.
•Tear Film Breakup Time: Measured before
contact lens application and generally performed
with fluorescein, an average of two or more readings
in seconds should be taken with the biomicroscope.
Tear film breakup time can also be measured using
the Keratograph 5M (Oculus Inc.).
• Corneal Staining (fluorescein): Extent and location graded from 0 to 4.
www.clspectrum.com
• Conjunctival Staining (lissamine green): Extent
and location graded from 0 to 4.
• Bulbar, Limbal and Eyelid Margin Hyperemia:
Graded from 0 to 4.
• Palpebral Conjunctival Evaluation:
– Hyperemia, roughness, papillary response
graded from 0 to 4.
– GPC graded from 0 to 4.
• Lid Wiper Epitheliopathy: Graded from 0 to 4.
• Meibomian Gland Evaluation:
– Function (e.g., oil availability upon light
pressure).
– Secretion quality graded from 0 to 4.
– Appearance (e.g., orifice capping, telangiectasia, etc.).
• Meibography: Graded from 0 to 4; can be
performed via transillumination or with a
meibographer.
• Blink Completeness
• Tear Osmolarity: Scores greater than
307mOsm/L indicate dry eye.
• Contact Lens Surface Wettability: Graded from
0 to 4.
• Schirmer or Phenol Red Thread Test: Recorded in mm/min. or seconds.
For more insights, see “Clinical Patterns Aid Assessment.”
What Are We to Do?
While some patients experience CLD symptoms
only in certain environments, such as the extremely
low humidity in an airplane, others experience severe
and constant symptoms that lead to termination of
contact lens wear. Thus, while we can choose from
numerous management strategies, we must be mindful that each patient is unique, and a tailored medical
management approach, including ocular surface and
lid assessment or if indicated, temporary or permanent cessation of lens wear, may be necessary. Treatment options include the following:
•Adjust Ambient and External Environment:
Increased periocular humidity can have a dramatic
and positive effect on the prelens tear film and contact lens comfort. Experiments with goggles to control evaporation have demonstrated decreased
evaporation of the tear film thinning rates23 and reduced corneal epithelial erosions.24
These results continue to affirm what we know is
the key to increasing ocular comfort during contact
lens wear: a robust tear film with an adequate lipid
layer and a healthy blink mechanism. A tear film that
is adequate or marginally adequate without a contact
lens may not be adequate in the presence of a contact
CONTACT LENS SPECTRUM/SPECIAL EDITION 2013 •
21
CONTACT LENS COMFORT
lens. Work environment, room humidity,
outdoor humidity/aridness and drying
Clinical Patterns Aid Assessment
environments (heating/air conditioning)
he broad range of ocular signs associated with CLD couall play a role and can be discussed with
patients. Indoor humidifiers and appropled with a potential lack of correlation between signs and
priate placement of computer monitors
symptoms underscore the need for a variety of tests to
in the workplace can have a noticeable
screen for CLD.5
impact on a contact lens patient’s comAn equally important part of the clinical workup is uncovfort and may be important in the overall
ering
symptoms that may be associated with CLD. By roumanagement plan.
tinely administering surveys or asking specific questions
• Recommend Rewetting Drops:
Rewetting drops may help relieve sympabout each patient’s lens-wearing experience, you can obtoms of dryness and improve for some
tain valuable information that reveals the presence and
individuals however, patients may view
severity of dryness, for example:
them as inconvenient if they must use
• Reduced overall satisfaction with lens wear
them frequently. Numerous brands of
• Inability to wear lenses as long as desired
contact lens rewetting drops are available
• Use of rewetting drops
to consumers. We believe eyecare professionals should recommend a specific
• Recent contact lens refitting to improve comfort or
product, including instructions for use.
other symptoms.33
•Change Lens Replacement Interval:
This information can help paint a clinical picture that
Patients with CLD may benefit from repoints toward CLD, even when signs and symptoms fail to
placing their lenses more frequently.
correlate.
When compared with frequent replacement (1 to 3 months) and 2-week replacement lenses, daily disposable hydrogel lenses
number of functional meibomian glands than nonshowed fewer lens surface deposits, and wearers relens wearers. 29 One implication that the authors
25
ported better comfort and overall satisfaction. Daily
make is that the mechanical interaction between the
disposable hydrogel lenses may also help alleviate
lids and contact lens surface may lead to an atrophy
end-of-day dryness symptoms.26
of some of the meibomian glands. Thus, it seems
•Change Lens Material: Certain polymers and reasonable to look at material characteristics such as
surface treatments provide better wettability and a
coefficient of friction to help reduce the mechanical
more normal prelens tear film than others. Refitting
interaction and frictional drag between the lens and
soft lens wearers who have CLD symptoms into silithe lid as much as possible.
cone hydrogel materials may improve comfort. A
• Change Care Regimen: When contact lens
study found that patients who had CLD symptoms
wearers complain of discomfort, practitioners often
and were wearing soft lenses experienced significantchange contact lens disinfecting solutions. Rely improved dryness and comfort, and they increased
searchers have found a particular brand of multipurtheir comfortable wearing time after they were refit
pose solutions (MPS) may provide improved overall
with a silicone hydrogel material.6 In addition, we
and end-of-day comfort and overall satisfaction for a
have found that patients may be more comfortable
lens wearer when compared to other MPS brands.4,30
with a lower modulus silicone hydrogel lens, or even
Changing a patient’s care regimen from an MPS sysa conventional hydrogel lens, if they find a higher
tem to a hydrogen peroxide-based system may result
modulus silicone hydrogel lens uncomfortable. Addiin longer comfortable lens wear times.31 As with
tional recent studies have concluded that mechanical
many aspects of clinical practice, each lens wearer reproperties, such as the coefficient of friction of a
sponds differently to each solution. Therefore, an inlens, surface lubricity and lens stiffness are properties
dividualized approach may be necessary to find the
driving lens comfort.27,28 For instance, we know that a
most appropriate lens care solution.
contact lens wearer will blink thousands of times a
•Discuss Essential Fatty Acid Supplementation:
day, leading to a repeated mechanical interaction bePatients with CLD have reported improved symptoms
tween the eyelid and contact lens surface and edge.
of dryness and increased overall comfort, and they have
There has been at least one study that has showed
demonstrated improved tear meniscus height while usthat a contact lens wearer has a reduction in the
ing omega-3 and omega-6 dietary supplements.32
T
22
•
CONTACT LENS SPECTRUM/SPECIAL EDITION 2013
www.clspectrum.com
CONTACT LENS COMFORT
Adding to the CLD Armamentarium
Our understanding of CLD has advanced during
the past several years. We can now direct our efforts
toward alleviating these symptoms to multiple areas:
new lens polymers, 1-day lenses, lens care products
and methods to prevent evaporation, treatments for
References
1. Nichols JJ, Ziegler C, Mitchell GL, Nichols KK. Self-reported dry eye disease across refractive modalities. Invest Ophthalmol Vis Sci 2005;46:1911-1914.
2. Richdale K, Sinnott LT, Skadahl E, Nichols JJ. Frequency of
and factors associated with contact lens dissatisfaction and
discontinuation. Cornea 2007;26:168-174.
3. Begley CG, Chalmers RL, Mitchell GL, et al. Characterization of ocular surface symptoms from optometric practices in
North America. Cornea 2001;20:610-618.
4. Corbin GS, Bennett L, Espejo L, Carducci S, Sacco A, Hannigan R, Schatz S. A multicenter investigation of OPTIFREE RepleniSH multi-purpose disinfecting solution
impact on soft contact lens patient comfort. Clin Ophthalmol
2010;4:47-57.
5. Young G, Chalmers R, Napier L, Kern J, Hunt C, Dumbleton K. Soft contact lens-related dryness with and without
clinical signs. Optom Vis Sci 2012;89:1125-1132.
6. Riley C, Young G, Chalmers R. Prevalence of ocular surface
symptoms, signs, and uncomfortable hours of wear in contact lens wearers: the effect of refitting with daily-wear silicone hydrogel lenses (senofilcon a). Eye Contact Lens
2006;32:281-286.
7. Nichols JJ, Sinnott LT. Tear film, contact lens, and patientrelated factors associated with contact lens-related dry eye.
Invest Ophthalmol Vis Sci 2006;47:1319-1328.
8. Dumbleton K, Woods CA, Jones LW, Fonn D. The impact
of contemporary contact lenses on contact lens discontinuation. Eye & Contact Lens 2013;39(1):93-99.
9. Korb DR. Tear film–contact lens interactions. Adv Exp Med
Biol 1994;350:403-410.
10. Tomlinson A, Cedarstaff T. Tear Evaporation from the Human Eye - Effect of Contact Lens Wear. J Brit Contact Lens
Assoc 1982;5:141-150.
11. Young G, Efron N. Characteristics of the pre-lens tear films
during hydrogel contact lens wear. Ophthalmic Physiol Opt
1991;11:53-58.
12. Korb DR, Greiner JV, Herman JP, et al. Lid-wiper epitheliopathy and dry-eye symptoms in contact lens wearers.
CLAO J 2002;28:211-216.
13. Holden BA, Williams L, Sweeney DF, Swarbrick HA. The
endothelial response to contact lens wear. CLAO J
1986;12:150-152.
14. Carney L, Hill R. Variation in blinking with soft lens wear.
Int Cont Lens Clin 1984;11(4):250-253.
15. Linton RG, Curnow DH, Riley WJ. The meibomian glands:
an investigation into the secretion and some aspects of the
physiology. Br J Ophthalmol 1961;45:718-723.
16. Korb DR, Henriquez AS: Meibomian gland dysfunction and
contact lens intolerance. J Am Optom Assoc 1980;51:243-251.
17. Paugh JR, Knapp LL, Martinson JR, et al. Meibomian therapy in problematic contact lens wear. Optom Vis Sci
1990;67:803-806.
www.clspectrum.com
LWE, and, most importantly, the treatment of the
meibomian glands to improve their secretion by various methods. With current treatments and new advances still in the pipeline, the future appears
promising for reducing discomfort so that our patients can wear their contact lenses long term. CLS
18. Nichols KK, Foulks GN, Bron AJ, et al. The international
workshop on meibomian gland dysfunction: executive summary. Invest Ophthalmol Vis Sci 2011;52:1922-1929.
19. Foulks GN. Contact lens-induced dry eye. 2009:
http://www.eyecareeducators.com/site/contact_lens_induced_dry_eye.htm. Accessed January 22, 2013.
20. Thai LC, Tomlinson A, Doane MG. Effect of contact lens
materials on tear physiology. Optom Vis Sci 2004;81:194-204.
21. Nichols JJ, Mitchell GL, Nichols KK, Chalmers R, Begley
C. The performance of the contact lens dry eye questionnaire as a screening survey for contact lens-related dry eye.
Cornea 2002;21:469-475.
22. Korb DR, Herman JP, Greiner JV, et al. Lid wiper epitheliopathy and dry eye symptoms. Eye Contact Lens
2005;31(1)2-8.
23. Kimball SH, King-Smith PE, Nichols JJ. Evidence for the
major contribution of evaporation to tear film thinning between blinks. Invest Ophthalmol Vis Sci 2010;51:6294-6297.
24. Holden BA, Sweeney DF, Seger RG. Epithelial erosions
caused by thin high water content lenses. Clin Experiment
Optom 1986;69:103-107.
25. Solomon OD, Freeman MI, Boshnick, EL, et al. A 3-year
prospective study of the clinical performance of daily disposable contact lenses compared with frequent replacement and
conventional daily wear contact lenses. CLAO J
1996;22:250-257.
26. Peterson RC, Wolffsohn JS, Nick J, Winterton L, Lally J.
Clinical performance of daily disposable soft contact lenses
using sustained release technology. Cont Lens Anterior Eye
2006;29:127-134.
27. Brennan NA. Contact lens-based correlates of soft lens
wearing comfort. Optom Vis Sci 2009;86:E-abstract 90957.
28. Coles C, Brennan NA. Coefficient of friction and soft contact lens comfort. Optom Vis Sci 2012;89. E abstract 125603
29. Arita R, Itoh K, Inoue K, Kuchiba A, Yamaguchi T, Amano
S. Contact lens wear is associated with decrease of meibomian glands. Ophthalmology 2009;116(3):379-384.
30. Campbell R, Kame G, Leach N, Paul M, White E, Zigler L.
Clinical benefits of a new multipurpose disinfecting solution
in silicone hydrogel and soft contact lens users. Eye Contact
Lens 2012;38:93-101.
31. Keir N, Woods CA, Dumbleton K, Jones L. Clinical performance of different care systems with silicone hydrogel contact lenses. Cont Lens Anterior Eye 2010;33:189-195.
32. Kokke KH, Morris JA, Lawrenson JG. Oral omega-6 essential fatty acid treatment in contact lens associated dry eye.
Cont Lens Anterior Eye 2008;31:141-146; quiz 170. 2.
33. Ramamoorthy P, Sinnott LT, Nichols JJ. Treatment, material, care, and patient-related factors in contact lens-related
dry eye. Optom Vis Sci 2008;85:764-772.
CONTACT LENS SPECTRUM/SPECIAL EDITION 2013 •
23
It’s not always
this obvious
47% of lens sleepers aren’t telling you
how often they sleep in their lenses1
Talk to your patients about AIR OPTIX® NIGHT & DAY® AQUA
contact lenses.
**
2
AIR OPTIX® NIGHT & DAY® AQUA
Contact Lenses
Learn more about the lens approved for up to 30 nights
of continuous wear at myalcon.com
*AIR OPTIX® NIGHT & DAY® AQUA (lotrafilcon A) contact lenses: Dk/t = 175 @ -3.00D. Other factors may impact eye health. **Extended wear for up to 30 continuous nights, as prescribed
by an eye care practitioner.
Important information for AIR OPTIX® NIGHT & DAY® AQUA (lotrafi lcon A) contact lenses: Indicated for vision correction for daily wear (worn only while awake) or extended wear
(worn while awake and asleep) for up to 30 nights. Relevant Warnings: A corneal ulcer may develop rapidly and cause eye pain, redness or blurry vision as it progresses. If left untreated,
a scar, and in rare cases loss of vision, may result. The risk of serious problems is greater for extended wear vs. daily wear and smoking increases this risk. A one-year post-market study
found 0.18% (18 out of 10,000) of wearers developed a severe corneal infection, with 0.04% (4 out of 10,000) of wearers experiencing a permanent reduction in vision by two or more rows
of letters on an eye chart. Relevant Precautions: Not everyone can wear for 30 nights. Approximately 80% of wearers can wear the lenses for extended wear. About two-thirds of wearers
achieve the full 30 nights continuous wear. Side Effects: In clinical trials, approximately 3-5% of wearers experience at least one episode of infiltrative keratitis, a localized inflammation
of the cornea which may be accompanied by mild to severe pain and may require the use of antibiotic eye drops for up to one week. Other less serious side effects were conjunctivitis,
lid irritation or lens discomfort including dryness, mild burning or stinging. Contraindications: Contact lenses should not be worn if you have: eye infection or inflammation (redness
and/or swelling); eye disease, injury or dryness that interferes with contact lens wear; systemic disease that may be affected by or impact lens wear; certain allergic conditions or using
certain medications (ex. some eye medications). Additional Information: Lenses should be replaced every month. If removed before then, lenses should be cleaned and disinfected
before wearing again. Always follow the eye care professional’s recommended lens wear, care and replacement schedule. Consult package insert for complete
information, available without charge by calling (800) 241-5999 or go to myalcon.com.
References: 1. In a survey of 284 daily and extended wear contact lens patients. Alcon data on file, 2012. 2. In a survey of 311 optometrists in the U.S.;
Alcon data on file, 2012.
See product instructions for complete wear, care, and safety information.
© 2013 Novartis 1/13 AND13001JAD
LUBRICITY
The Clinical Relevance
of Contact Lens Lubricity
Using science to provide better comfort
for contact lens wearers.
By Desmond Fonn, MOptom, FAAO
D
Dr. Fonn is Founding Director
of the Centre for Contact
Lens Research and Distinguished Professor Emeritus
at the School of
Optometry. He is a graduate
of the School of Optometry
in Johannesburg, South
Africa and the University
of New South Wales in
Sydney, Australia. He is the
immediate Past President of
the International Society for
Contact Lens Research and a
founding member of the
International Association of
Contact Lens Educators in
which he served as Vice
President for 15 years.
He is a paid consultant of
Alcon and CooperVision.
www.clspectrum.com
espite advances in contact lens materials, designs and lens care
products, discomfort, especially end-of-day discomfort and dryness, continues to be
the predominant reason for discontinuation of lens wear.1,2 Although much effort has been put into development of
effective multifocal soft contact lenses,
contact lenses to control myopic progression and attempts to decrease
corneal infection rates, the most effective way to increase the number of
wearers is a corneo-mimetic contact
lens surface that provides outstanding
end-of-day comfort and therefore significantly reduce the number of
dropouts from contact lens wear.
Most soft lenses are fully hydrated
and comfortable upon insertion. We
know however that for many lens wearers comfort decreases or dryness worsens during the day3-5 and the maximal
fluid state of the ocular environment
and conventional hydrogel and silicone
hydrogel lenses can change6-8 after insertion. So the challenge for polymer
scientists, mechanical engineers and
everyone else associated with material
and lens development, is how to prevent loss of water from the lens surface
and therefore the bulk, or more appropriately how to effectively make the
surfaces truly biocompatible. Some
manufacturers have claimed to achieve
some of these objectives described further in this article, but before that it is
worth describing some of physical and
mechanical terms associated with lens
surfaces and their interaction with ocular tissue.
Tribology
Tribology, a domain of mechanical
engineering, is the science of friction,
lubrication and wear (not as in contact
lens wear, but deterioration). It is the
study of interacting surfaces in relative motion. Subbaraman and Jones9
have described how friction and lubricity can be measured.
Friction
Friction can be defined as the “resistance developed between contacting
surfaces when one of the bodies
moves, or tends to move, over the
other”10 The Coefficient of Friction
(COF) is a scaled value which describes the ratio of the force of friction between two surfaces and the
force pressing them together. The
value depends in part on the materials.
CONTACT LENS SPECTRUM/SPECIAL EDITION 2013 •
25
LUBRICITY
Two useful examples are: ice on steel, which would
have a low COF, while rubber on asphalt would have
a high coefficient of friction. There are several types
of friction / lubrication in the context of contact lens
wear. Hydrodynamic lubrication is where a fluid film
completely separates two solid surfaces. Boundary lubrication occurs when the two surfaces come into direct contact. Two contrasting contact lens examples
are the lid traversing a soaked hydrogel lens on the
eye at high speed (hydrodynamic lubrication) which
would have a relatively low COF but if the tear film is
completely dehydrated or the movement speeds are
low the COF would be considerably higher (boundary lubrication).
Lubricity
Lubricity can be thought of as the reciprocal of friction.
That is when friction is low, lubricity is high. A hydrogel contact lens surface in its dehydrated state is not
particularly lubricious, however, introducing a fluid
even with very low viscosity or soaking the lens in solution will improve the lubricity and reduce friction when
the eyelid slides across the lens surface. The ability of
the surface to retain moisture will affect the lubricity.
Wettability
This is a more commonly used term in the contact
lens world and is used to characterize the adherence
of fluid to the lens surface. Wettability can be an invitro (or ex-vivo) measure of the contact angle (CA)
or a clinical in-vivo assessment of pre-lens tear break
up time (TBUT) measurement. Although these are
frequently quoted values, there are other key factors
that may correlate better with comfort of contact
lenses. Maldonado-Codina and Efron 11 suggested
that the in-vivo interaction of tears and the lens surface cannot be predicted by CA measurements. Hysteresis (difference between the advancing and
receding contact angles) seems to be a better way of
expressing the laboratory wettability of lenses and
Tighe has shown that hysteresis values of uncoated
silicone hydrogels launched in recent years have decreased significantly, in part due to the markedly
greater water content.12
Clinical Consequences
of High Coefficient of Friction
It is fair to say that the advancements made in contact lens science and technology have eliminated or
minimised many of the complications that pre-dated
disposable lenses. Most of those complications were
associated with deposition of denatured protein and
other lens contaminants, giving rise to auto-immune
26
•
CONTACT LENS SPECTRUM/SPECIAL EDITION 2013
reactions, mechanical irritation of the tarsal conjunctiva and other ocular tissue, and in some cases, considerable discomfort. Loss of lubricity and increased
friction as a result of lens surface contamination were
likely responsible for these adverse ocular surface reactions. As lens technology continues to advance it is
important to measure the friction not only of fresh
lenses but to determine how lens friction changes in
response to wearing time and surface deposits.
One of the more dramatic ocular complications
that typifies the above description is giant papillary
conjunctivitis (GPC) or what is now termed contact
lens papillary conjunctivitis (CLPC). GPC was first
reported by Thomas Spring in 1974 as an inflammatory reaction of the palpebral conjunctiva more often
observed on the upper lid.13 Large (or “Giant”) papillae, palpebral hyperaemia and mucus secretion are
characteristic of the condition.14 Symptoms include
itching, ocular discomfort and poor, variable vision
which frequently led to discontinuation of wear. It
was not uncommon to observe an apparently dehydrated contaminated lens move 4 or 5 mm with a
normal blink, obviously due the loss of lubricity between the lens and palpebral surfaces. With current
lenses and good habits of frequent replacement these
findings are quite rarely encountered.
Through the development phase of silicone hydrogel lenses, CLPC has been reported to occur
more frequently (especially with continuous wear)
than with conventional hydrogel lenses and less with
newer silicone hydrogels than first generation.15 In
addition to the design and modulus changes, one
would have to suspect that increased water content
and methods to retain surface moisture has helped to
decrease the incidence of CLPC.
Coincident with the development of silicone hydrogel lenses, new clinical conditions have been reported.
In 2002, Korb and colleagues described a condition
called lid-wiper epitheliopathy (LWE) which is a band
of affected tissue of the marginal conjunctiva of the upper eyelid that wipes the ocular surface. The condition
is diagnosed by staining with fluorescein, rose bengal
or lissamine green. They found that contact lens wearers who were symptomatic of dryness had a significantly higher percentage of lid-wiper staining compared to
asymptomatic wearers.16
Pult and colleagues described a condition called
lid-parallel conjunctival folds (LIPCOF) which are
sub-clinical folds of the bulbar conjunctiva above and
parallel to the lower lid margin.17 It appears that this
condition is also more prevalent in symptomatic contact lens wearers but can also be detected in patients
with dry eye who do not wear contact lenses.
www.clspectrum.com
LUBRICITY
The suspected etiology of both LWE and LIPCOF is mechanical and in the case of LWE, the
tarsal conjunctiva is subjected to increased frictional
force or reduced lubricity of the contact lens surface
causing micro trauma to epithelial cells. This could
be aggravated by a lack of lubrication from tears.
The factor these more subtle contact lens related
conditions appear to have in common with GPC appears to be reduced lubricity, which probably provokes the symptoms of discomfort and dryness.
Efforts to Increase Lubricity
A number of attempts to increase the wettability of the
lens or to retain its moisture during the wearing period
appear to have been somewhat successful. Examples of
incorporating wetting agents into lens materials are
polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP)
and hyaluronic acid. These substances have also been
used in artificial tears and contact lens rewetting drops.
PVP acts as a hydrophilic layer thereby shielding the
hydrophobic properties of silicone hydrogel lenses.
Other humectants (substances that help to retain water)
such as hydroxypropyl methylcellulose (HPMC) and
polyethylene glycol (PEG) have been shown to im-
prove wettability of silicone hydrogel lenses. Keir and
Jones have eloquently and more extensively described
this topic.18 However it is unknown whether these wetting agents have had a lasting effect on lubricity.
The most recent development in daily disposable
silicone hydrogel technology is termed a water gradient lens*, ranging from 33% water content in the
core to approximately 80% at the surface.19,20 Gel layers that are minimally crosslinked (5-6 µm thick) are
graded on the surfaces of silicone hydrogel contact
lenses.20 Sawyer concluded that these gel layers provide a lubricious surface with very low friction coefficients (below µ = 0.01).
Finally, the most compelling evidence of a measureable lens variable that correlates with end-of-day
comfort is the coefficient of friction, demonstrated
by Brennan and Coles in two separate studies.21,22 The
efforts of measuring and modifying lens surfaces that
truly retain moisture and lubricity throughout the
day could be the most important development since
the Wichterle soft lens, perhaps even surpassing the
discovery of the silicone hydrogel material. CLS
*Based on in-vitro measurement of unworn lenses.
References
1. Dumbleton K, Woods CA, Jones LW, Fonn D. The impact
of contemporary contact lenses on contact lens discontinuation. Eye Contact Lens 2013;39(1):93-99.
2. Rumpakis J. New data on contact lens dropouts: an international perspective. Review of Optometry 147; 2010: 37-42.
3. Fonn D, Situ P, Simpson TL. Hydrogel lens dehydration
and subjective comfort and dryness ratings in symptomatic
and asymptomatic contact lens wearers. Optom Vis Sci
1999;76(10):700-704.
4. Guillon M, Maissa C. Dry eye symptomatology of soft contact lens wearers and non-wearers. Optom Vis Sci
2005;82(9):829-834.
5. Chalmers RL, Begley CG. Dryness symptoms among an unselected clinical population with and without contact lens
wear. Cont Lens Anterior Eye 2006;29(1):25-30.
6. Cedarstaff TH, Tomlinson A. A comparative study of tear
evaporation rates and water content of soft contact lenses.
Am J Optom Physiol Opt 1983;60(3):167-174.
7. Pritchard N, Fonn D. Dehydration, lens movement and dryness ratings of hydrogel contact lenses. Ophthalmic Physiol Opt
Morgan PB, Efron N. In vivo dehydration of silicone hydrogel contact lenses. Eye Contact Lens 2003;29(3):173-176.
9. Subarraman L, Jones LW. Measuring friction and lubricity
of hydrogel contact lenses – A review. Contact Lens Spectrum;
Special edition 2013 (in press).
10. Malhotra M, Subramanian R, Gahlot P, Rathore B. Textbook in Applied Mechanics. New Delhi: New Age International; 1994.
11. Maldonado-Codina C, Efron N. Dynamic wettability of
pHEMA-based hydrogel contact lenses. Ophthalmic Physiol
Opt 2006;26(4):408-418.
www.clspectrum.com
12. Tighe BJ. A decade of silicone hydrogel development: surface
properties, mechanical properties and ocular compatibility.
Eye Contact Lens 2013;39(1):4-12.
13. Spring TF. Reaction to hydrophilic lenses. Med J Aust
1974;1(12):449-450.
14. Allansmith MR, Korb DR, Greiner JV, Henriquez AS, Simon
MA, Finnemore VM. Giant papillary conjunctivitis in contact lens wearers. Am J Ophthalmol 1977;83(5):697-708.
15. Dumbleton K. Noninflammatory silicone hydrogel contact
lens complications. Eye Cont Lens 2003;29(1 Suppl):S186189;discussion S190-191, S192-194.
16. Korb DR, Greiner JV, Herman JP, et al. Lid-wiper epitheliopathy and dry-eye symptoms in contact lens wearers.
CLAO J 2002;28(4):211-216.
17. Pult H, Purslow C, Berry M, Murphy PJ. Clinical tests for
successful contact lens wear: relationship and predictive potential. Optom Vis Sci 2008;85(10):E924-929.
18. Keir N, Jones L. Wettability and silicone hydrogel lenses: A
review. Eye Contact Lens 2013;39(1)100-108.
19. Pruitt J, Qiu Y, Thekveli S et al. Surface characterization of a
water gradient silicone hydrogel contact lens (delefilcon A).
Invest Ophthal Vis Sci 2012; 53. E-abstract 6107.
20. Sawyer WG. Lubricity in high water content surface gel layers. Optom Vis Sci 2012;89. E-abstract 125089.
21. Brennan, N.A., Contact Lens-based correlates of soft lens
wearing comfort. Optom Vis Sci 2009;86. E-abstract 90957.
22. Coles C. Coefficient of friction and contact lens comfort. Optom Vis Sci 2012;89. E-abstract 125603.
CONTACT LENS SPECTRUM/SPECIAL EDITION 2013 •
27
EXPLORING COMFORT
Measuring Friction and
Lubricity of Soft Contact
Lenses: A Review
Comfort may be tied to friction and lubricity.
By Lakshman N Subbaraman, PhD, BSOptom, MSc, FAAO,
& Lyndon W Jones, PhD, FCOptom, FAAO
Dr. Subbaraman is Head of
Biological Sciences at the
Centre of Contact Lens
Research, School of Optometry,
University of Waterloo. He is a
consultant/advisor to Alcon
and Johnson & Johnson. He
has received grants from Alcon,
Allergan, Bausch + Lomb,
CooperVision, Johnson &
Johnson, TearScience, Essilor
and Visioneering.
Dr. Jones is a Professor at the
School of Optometry and
Vision Science and Director
of the Centre for Contact Lens
Research at the University of
Waterloo. He is a
consultant/advisor to Alcon
and Johnson & Johnson. He
has received grants from Alcon,
Allergan, Bausch + Lomb,
CooperVision, Johnson &
Johnson, TearScience, Essilor
and Visioneering.
28
•
Over the last 35 years, the number
of contact lens wearers worldwide has
increased from 10 million to 140 million, with the vast majority (over
90%) being fitted with soft lenses. 1
Recent reports suggest that the contact lens industry is healthy and the
worldwide annual soft contact lens
market is estimated at $5.3 billion,
with the U.S. market estimated at
$1.9 billion.2 However, despite this
apparently buoyant position, many
wearers continue to be dissatisfied
with their lenses and approximately
35% of lens wearers discontinue wear,
with the majority reporting the major
reasons being discomfort and dryness,
particularly at the end of the day. 3
Contact lens-related discomfort and
dryness is influenced by several factors, and likely include both the interaction of the posterior surface of the
lens with the corneal surface and the
anterior surface of the contact lens
with the posterior surface of the eyelid during the blink.
Hydrogel lenses rapidly attract various components from the tear film,
particularly proteins and lipids, following their insertion.4 These can re-
CONTACT LENS SPECTRUM/SPECIAL EDITION 2013
sult in alterations to the surface of the
contact lens that can change the frictional forces that exist during blinking. Furthermore, dehydration of
lenses can result in increased lid-lens
interaction due to a reduction in lens
front-surface wettability and lubricity,
and the development of corneal epithelial staining due to pervaporation
and subsequent desiccation.5 Studies
have suggested that the frictional
properties of contact lenses may also
be associated with certain clinically
observable phenomena, notably lid
wiper epitheliopathy and lid parallel
conjunctival folds.6,7 Finally, increased
friction may lead to contact lens associated papillary conjunctivitis due to
the mechanical interaction of the
palpebral conjunctiva with the contact
lens surface.8
Issues such as these have made it
clear that the frictional properties of
lenses are an important design consideration in the fabrication and manufacture of soft lenses. Furthermore,
understanding the frictional forces that
occur at the lens surface will provide
insight into the relationship between
the lens material surface properties and
www.clspectrum.com
Contact Lens Spectrum
6/13
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Alcon offers the DAILIES® family of daily disposable contact lenses and
the AIR OPTIX® family of monthly replacement lenses. Multiple studies
have shown that daily disposable and monthly replacement contact lens
wearers are more compliant* than those who wear 2-week lenses.2,3,4
Compliant patients also return for more eye examinations.1
Read more about this latest study, and see how Alcon
can boost your practice, at myalcon.com/power-of-one
*Compliance with Manufacturer-Recommended Replacement Frequency (MRRF).
References: 1. Dumbleton KA, Richter D, Jones LW. Compliance with lens replacement and the interval between eye examinations.
Optom Vis Sci. 2012;89 (E-abstract 120059). 2. Dumbleton K, Woods C, Jones L, et al. Patient and practitioner compliance with silicone
hydrogel and daily disposable lens replacement in the United States. Eye & Contact Lens. 2009;35(4):164-171. 3. Yeung KK, Forister JFY,
Forister EF, et al. Compliance with soft contact lens replacement schedules and associated contact lens–related ocular complications:
The UCLA Contact Lens Study. Optometry. 2010; 81(11):598-607. 4. Dumbleton K, Woods C, Jones L, et al. Comfort and Vision with Silicone
Hydrogel Lenses: Effect of Compliance. Optom Vis Sci. 2010;87(6):421-425.
MORE POWER
FOR GREATER SUCCESS
See product instructions for complete wear, care, and safety information.
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81924 POW12060JAD CLS.indd 1
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EXPLORING COMFORT
biological responses such as protein deposition and
bacterial adhesion.9 However, to-date, very few studies
report on the frictional characteristics of soft lenses10-16
and contact lens practitioners may be unaware of the
relevance of this factor to everyday practice. The
scope of this review article is to provide an overview of
various methods that have been employed to determine the friction of hydrogel lenses.
Terminology
Material scientists and researchers who work on the surface properties of lens materials commonly use terms
such as “tribology”, “friction” and “lubricity.” However,
eye care practitioners may not be familiar with these
terms as they do not use them on a day-to-day basis and
a description of these terms is valuable.
Tribology comes from the Greek word “tribos,”
which means “to rub.” Tribology is generally defined
as the study of three areas — friction, lubrication and
wear. These three areas are highly inter-related; however, the relationship between friction and wear is not
well understood. Generally, friction is produced
when two sliding surfaces come into contact, resulting in wear. Wear can be prevented by lubrication,
and the separation of the surfaces by a lubricant will
result in a reduction in friction. The purpose of tribological research is to minimize friction and wear,
therefore, tribology plays a major role in the effective
treatment of some of the common medical conditions
involving bodily implants and joint diseases.
Biotribology is a relatively new term introduced
in the early 1970s to describe a group of sciences that
focus on one single topic — the study of friction,
wear and lubrication within biology. This is a multidisciplinary subject covering the areas of engineering, material science, biological science, physical
science and medicine.
Friction can be defined as the force that acts at
the surface of two solid surfaces to resist sliding over
one another. The force that prevents one surface
sliding over the other is quantified by a simple index
called the coefficient of friction (CoF). In order to
determine CoF, two measurements are needed: (a)
the force required to initiate and/or sustain sliding
and (b) the normal force holding the two surfaces together. CoF can then be calculated by dividing the
initiating/sustaining force by the normal force. A lubricant can be used to reduce friction between two
surfaces. Since a lubricant reduces friction, CoF is an
easy measure of quantifying the lubricating ability of
any system. Generally, a comparison between CoF
generated by an instrument under identical conditions is acceptable. However, comparing CoF values
30
•
CONTACT LENS SPECTRUM/SPECIAL EDITION 2013
from different instruments under different conditions should be interpreted with caution.
Lubrication is defined as any means capable of
controlling friction and wear of interactive surfaces
in relative motion. There are two types of lubrication; one where there is a solid-to-solid contact of
the sliding surfaces is known as “boundary lubrication” and the other where there is a thin layer of fluid that is present in the intervening space
(hydrostatic lubrication) or the motion produces a
layer of fluid on which the moving surface planes
over the counter face (hydrodynamic lubrication).
Biotribology is a relatively
new term introduced in the
early 1970s to describe a
group of sciences that focus
on one single topic — the
study of friction, wear and
lubrication within biology.
Methods of Measuring Friction and Lubricity
The most common method for determining the CoF
of soft contact lenses is through the use of a “microtribometer.” Some researchers have used a method
based on atomic force microscopy15,16 and others have
developed novel proprietary techniques17 to determine
the lubricity of contact lenses and the following section describes these various methods.
Microtribometer
A microtribometer is an instrument that directly
measures the frictional force and the normal force in
order to calculate the coefficient of friction. Many
different parameters must be controlled to generate
repeatable measurements and the following section
provides an outline of the parameters that influence
the CoF values obtained using a microtribometer.
Sliding speed: Test speeds have a large effect on
the measured COF and speeds as low as 0.01 mm/sec13
have been used to measure “boundary lubrication”,
which occurs when the lens is in direct contact with
www.clspectrum.com
EXPLORING COMFORT
Figure 1. Inclined plane method
the ocular tissues. Higher speeds approximating the
blink speed of 12 cm/sec have been used10 to measure
“mixed” or “hydrodynamic lubrication”, where a thin
fluid film separates the contact lens from the ocular
tissues. Studies have used a wide range of sliding
speeds (63 to 6280 µm/sec,11 0.01 to 0.5cm/sec,12 or
10 to 600 µm/sec18) to determine the effect of sliding
speeds on the reported CoF values.
Normal Force Pressure: In-vivo eyelid pressures
are typically estimated at 1-7 kPa and achieving accurate force measurements at these low pressures can be
challenging. A recent study has determined frictional
values at very low contact pressures, approaching
1kPa.18
Substrate / Counter Surface: All friction measurements involve two surfaces and the choice of
substrate against which to determine the CoF can affect the reported results. Substrates utilized include
glass,11,18 stainless steel,12 or mucin-coated silanized
glass.13
Lubricating fluid: Nairn and colleagues10 used
various commercial ophthalmic solutions including
B+L ReNu, Allergan Complete, Alcon Opti-Free
and B+L saline and showed that differing lubricants
resulted in differences in the reported CoF values.
Artificial tear fluids and solutions containing a variety of tear proteins that mimic human tears have also
been used as lubricating fluids.13,14
Type of movement: Microtribometers typically
use either a flat plate or a curved probe that is moved
across the lens surface. The flat plate method maintains contact with only a single point on the contact
lens surface during testing,13 while the probe method
is able to expose fresh lens surface to the probe as the
www.clspectrum.com
probe is moved across the lens surface.18
Lens sample preparation: To-date, all published
CoF data has been conducted only on unworn
lenses. The effects of lens wear and contact lens care
solutions have not been adequately tested in order to
determine whether the coefficient of friction is likely
to change with time after exposure to tear film components and further work is warranted in this area.
Finger Lubricity Method
Recently, a qualitative “finger rubbing” method has
been described to determine contact lens lubricity.17
In this method, contact lenses were rinsed overnight
in a phosphate buffered saline (PBS) solution to remove any packaging solution, and the investigator
rubbed the lens between their thumb and index fingers and the lubricity was rated on a 0 (most lubricious) to 4 (least lubricious) scale. The advantage of
this method is that it is a simple, quick method that
does not require any sophisticated instrumentation.
The authors reported that this method was highly
repeatable, but only when used by an experienced investigator.17 A major disadvantage of this method is
that it is a limited qualitative scale and not all lens
types can be differentiated with this technique.
Inclined Plane Method (Figure 1)
This is a novel, quantitative method of determining
contact lens friction using a PBS solution.17 In this
method, a clean glass plate is adjusted to a desired
angle in a PBS bath. The contact lens under test is
placed at the top of the glass plate and a 0.8 gram
stainless steel ferrule (0.88 kPa) is placed on the lens
to initiate movement. A minimum critical angle is
CONTACT LENS SPECTRUM/SPECIAL EDITION 2013 •
31
(Image courtesy University of Florida)
EXPLORING COMFORT
Figure 2. Beam Deflection AFM
determined, which maintains the movement of the
lens over a distance of approximately 100 mm. The
tangent of the critical angle is a measure of the kinetic coefficient of friction. Thus, in this method, the
tangent of the largest angle where the lens is unable
to maintain movement will determine the kinetic coefficient of friction.17
Atomic Force Microscopy (Figure 2)
Atomic force microscopy (AFM) is a standard technique used to study the surface topography of conventional and silicone hydrogel contact lens
materials.19 AFM is a very powerful tool for high-resolution examination of the contact lens surface and
also permits the analysis of surface topography and
roughness by means of a non-destructive methodology. AFM consists of a microscale cantilever with a
sharp tip, which scans the surface of the lens. The
cantilever is typically made of silicon or silicon nitride with a tip radius of curvature in the order of
nanometers. The AFM can be operated in a number
of modes, including static (also called contact) mode
and a variety of dynamic (non-contact or tapping)
modes, where the cantilever is vibrated. The advantage of AFM over traditional microscopic techniques
is the high-resolution, three-dimensional images and
also that topographic information can be obtained in
32
•
CONTACT LENS SPECTRUM/SPECIAL EDITION 2013
several conditions (such as
aqueous, non-aqueous or
dry), thereby eliminating
the need for sample preparation.
Kim and colleagues15,16
used a contact-mode AFM
to determine the surface
properties of pHEMAbased soft contact lenses.
AFM images of the lens
surface were taken in two
conditions: (a) with the
lens surface exposed to air
(“surface-dehydrated”) and
(b) in the presence of
saline solution on the lens
surface. After successfully
optimizing a method to
quantify friction using
AFM, the authors concluded that the friction force
imaging of the “surfacedehydrated” soft contact
lenses made of cross-linked
pHEMA showed low friction at the surfaces. In saline, the surface friction was
significantly reduced compared to those measured
for the “surface-dehydrated” lens.15 In a recent study,
Rudy and colleagues20 determined the surface mechanical and tribological properties of silicone hydrogels using AFM. In this study, they measured the
elastic modulus by indenting a probe into the surface
of the hydrogel in a controlled manner and obtained
a modulus value by fitting the characteristic force
versus indentation behaviour. Their results showed
that pHEMA-based etafilcon A lenses have a modulus between 100 and 130 kPa, whereas balafilcon A
lenses were an order of magnitude higher in value.
The frictional properties followed a similar trend,
with plasma surface-treated lenses (such as balafilcon
A) exhibiting CoF values five times those of delefilcon A water gradient silicone hydrogels. These
studies show that the elastic modulus and frictional
properties of different hydrogel and silicone hydrogel lenses can be evaluated at a nanoscopic level using AFM.
Conclusions
Determining the frictional properties of soft lenses is
complicated and a review of the literature reveals
that there are several methods of determining the lubricity of contact lens materials. Due to the vast dif-
www.clspectrum.com
EXPLORING COMFORT
ference in techniques and methodology for determining friction, there are noticeable differences in
the coefficient of friction values published to-date.
Though significant differences do seem to exist
among lens materials, it remains challenging to make
comparisons until standard methods of testing are
agreed upon. Material chemistry, water content, test
media, applied load and the sliding velocity all have
an impact on the results, and may impact different
materials to varying degrees. Deposition of tear-derived components can also impact friction forces for
both silicone and conventional hydrogels and may be
a difficult condition to reproduce in an in vitro testing model and future studies should include testing
under conditions closer to that obtained in-eye.
A recent analysis that attempted to correlate several
contact lens material-related properties (Dk/t, modulus, water content and lubricity) with end-of-day
wearing comfort found coefficient of friction to be the
principal physical property associated with comfort.21
In this work, end-of-day comfort data obtained from
over 700 separate 1-month wearing trials were derived
using a sensitive and sophisticated method. The friction data showed consistently high correlation with
comfort, implicating that coefficient of friction could
be a major driving factor in subjective comfort. However, data from more carefully conducted clinical trials
are needed to determine the relationship between subjective symptoms of discomfort and dryness and the
lubricity of various commercial contact lens materials.
The influence of contact lens care regimens and how
they influence the friction values of contact lenses
should also be investigated. CLS
The authors would like to acknowledge Alcon Laboratories
Ltd, USA for their support in developing this article
through an unrestricted grant.
References
1. Morgan PB, Woods CA, Tranoudis IG, et al. International
contact lens prescribing in 2011. Contact Lens Spectrum;
January 2012.
2. Nichols JJ. Contact Lenses 2008. Contact Lens Spectrum;
January 2009.
3. Fonn D. Targeting contact lens induced dryness and discomfort: what properties will make lenses more comfortable. Optom Vis Sci 2007;84(4):279-285.
4. Bontempo AR, Rapp J. Protein and lipid deposition onto
hydrophilic contact lenses in vivo. CLAO J 2001;27(2):7580.
5. Pritchard N, Fonn D. Dehydration, lens movement and
dryness ratings of hydrogel contact lenses. Ophthalmic
Physiol Opt 1995;15(4):281-286.
6. Berry M, Pult H, Purslow C, Murphy PJ. Mucins and ocular signs in symptomatic and asymptomatic contact lens
wear. Optom Vis Sci 2008;85(10):E930-938.
7. Pult H, Purslow C, Berry M, Murphy PJ. Clinical tests for
successful contact lens wear: relationship and predictive
potential. Optom Vis Sci 2008;85(10):E924-929.
8. Donshik PC. Contact lens chemistry and giant papillary
conjunctivitis. Eye Contact Lens 2003;29(1 Suppl):S37-39;
discussion S57-59, S192-194.
9. Willcox MD, Harmis N, Cowell BA, Williams T, Holden
BA. Bacterial interactions with contact lenses; effects of
lens material, lens wear and microbial physiology. Biomaterials 2001;22(24):3235-3247.
10. Nairn JA, Jiang T. Measurement of the friction and lubricity properties of contact lenses. In: Proceedings of ANTEC 1995; May 7-11, 1995 in Boston.
11. Rennie AC, Dickrell PL, Sawyer WG. Friction coefficient
of soft contact lenses: measurements and modeling. Tribol
Lett 2005;18(4):499-504.
12. Zhou B, Li Y, Randall NX, Li L. A study of the frictional
properties of senofilcon-A contact lenses. J Mech Behav
Biomed Mater 2011;4(7):1336-1342.
www.clspectrum.com
13. Roba M, Duncan EG, Hill GA, Spencer ND, Tosatti SG.
Friction measurements on contact lenses in their operating
environment. Tribol Lett 2011;44:387-397.
14. Ngai V, Medley JB, Jones L, Forrest J, Teichroeb J. Friction of contact lenses: silicone hydrogel versus conventional hydrogel. Tribol Interface Eng Ser 2005;48:371-79.
15. Kim SH, Marmo C, Somorjai GA. Friction studies of hydrogel contact lenses using AFM: non-crosslinked polymers of low friction at the surface. Biomaterials
2001;22(24):3285-3294.
16. Kim SH, Opdahl A, Marmo C, Somorjai GA. AFM and
SFG studies of pHEMA-based hydrogel contact lens surfaces in saline solution: adhesion, friction, and the presence
of non-crosslinked polymer chains at the surface. Biomaterials 2002;23(7):1657-1666.
17. Tucker RC, Quinter B, Patel D, Pruitt J, Nelson J. Qualitative and quantitative lubricity of experimental contact
lenses. Invest Ophthalmol Vis Sci 2012;ARVO E-Abstract:6093.
18. Sawyer WG, Dunn AC, Uruena JM, Ketelson H. Robust
contact lens lubricity using surface gels. Invest Ophthalmol
Vis Sci 2012;ARVO E-abstract:6095.
19. Gonzalez-Meijome JM, Lopez-Alemany A, Almeida JB,
Parafita MA, Refojo MF. Microscopic observation of unworn siloxane-hydrogel soft contact lenses by atomic force
microscopy. J Biomed Mater Res B Appl Biomater
2006;76(2):412-418.
20. Rudy A, Huo H, Perry S, Ketelson H. Surface mechanical
and tribological properties of silicone hydrogels measured
by atomic force microscopy. Invest Ophthalmol Vis Sci
2012;ARVO E-abstract:6114.
21. Coles C, Brennan N. Coefficient of friction and soft contact lens comfort. Optom Vis Sci 2012;89:E-abstract:
125603.
CONTACT LENS SPECTRUM/SPECIAL EDITION 2013 •
33
Contact Lens Spectrum
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References: (1) Richer S, Stiles W, Statkute L, et al. Double-masked, placebo-controlled, randomized trial of lutein and antioxidant supplementation in the intervention
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MATERIALS
Introducing Water
Gradient Technology
Daily disposable contact lenses with water gradient
technology represent a new era in contact lens wear.
By Ralph Stone, PhD
C
Dr. Stone is one of the
foremost experts on contact
lens care product design and
formulation. A winner of the
prestigious Donald Korb
Award from the American
Optometric Association,
Contact Lens & Cornea
Section, he is often referred
to as the father of modern
contact lens care. Dr. Stone
is a former VP of research
and development for Alcon.
34
•
ontact lens materials have
evolved from PMMA
lenses of the 1950s to
oxygen permeable rigid
lenses of the 1980s and
beyond. The introduction of hydrogel
materials in the early 1970s brought
new levels of comfort. Disposable lenses in the 1990s evolved further with the
introduction of silicone hydrogels.
Material and manufacturing technologies have made possible daily disposable lenses, something that would have
been unthinkable in the early days of
soft lenses.
As materials evolved, it became useful to find a way to group these materials based on fundamental characteristics
including water content and the presence of ionic ingredients for hydrophilic
materials and by the hydrophobic components for the rigid hydrophobic materials 1. By 1994, FDA listed 34
different soft contact lens materials and
95 brands and 39 hydrophobic contact
lenses.1 These grouping systems served
the industry well through the both the
hydrophobic lens and hydrogel lens
eras, but with the introduction of silicone hydrogel materials, the system had
to be expanded to include these biphasic
materials.
CONTACT LENS SPECTRUM/SPECIAL EDITION 2013
A New Era
Since the introduction of silicone hydrogels in 1998, these materials have
become the dominant choice of fitting
practitioners.2,3 Today these materials
are considered to be a separate class of
hydrophilic contact lens materials and
experts from around the world are
evaluating if additional groups are
needed. 4 The latest introduction,
Dailies Total1 (delefilcon A) water
gradient daily disposable contact lenses by Alcon Laboratories, represents a
landmark in the continuing revolution
in contact lens materials that underscores the need for a new grouping
system, because this material is truly
in a class by itself as the first water
gradient silicone hydrogel contact
lens.
Dailies Total1 daily disposable
contact lenses have a revolutionary
structure based on a silicone hydrogel
core and a water gradient surface that
creates a transition from core water
content of 33% to a surface water
content in excess of 80% at the interface with the tear film. The surface of
the lens, like the corneal epithelium
and glycocalyx, has a brush-like structure that binds water in this region of
the lens. A water gradient is created
www.clspectrum.com
MATERIALS
crons, the water gradient surface represents slightly
more than 6% of the central lens thickness on each
side.6
The color change in the AFM image represents a
change in water content, modulus and chemical composition that is not seen in any other lenses tested. The
water gradient provides a lubricous lens surface that is
also substantially softer than the core of the lens.6
Beyond Oxygen
Figure 1. Schematic representation of Dailies Total1 water
gradient contact lenses.
With the development of materials and lens care systems over time, we have recognized that we can solve
some of the issues of contact lens lenses and lens wear
with improved technologies. The understanding of the
role of oxygen and transmission through the lens has
led to the creation of lenses that do not cause oxygen
deficiency at the cornea. It is now recognized that enhanced oxygen maintains corneal function and decreases edema and other changes due to hypoxia. Dailies
Total1 lenses have a central Dk/t of 156 at -3.00
diopters. This is the highest of the currently available
daily disposable contact lens materials. Table 1 shows a
comparison of Dk and central Dk/t of several daily disposable lens materials.
Oxygen has not solved all contact lens wear issues.
Despite advances made in lens materials to date, it
has been reported that nearly 15% percent of patients will stop wearing contact lenses every year. 7
The most common reasons reported for discontinuing wear are discomfort and dryness.8-11
Enhancing Comfort:
Modulus, Wettability, Lubricity
Figure 2. Atomic Force Microscopy cross-section image of
the Dailies Total1 contact lens.
by cross-linked polymeric wetting agents that form a
soft, hydrophilic surface gel, which is embedded into
the core, creating a smooth transition from the core
to the surface. The water gradient provides the lowest silicone surface content of any silicone hydrogel
lens material.
Figure 1 shows a representation of this novel approach.5 Figure 2 shows an Atomic Force Microscopy
(AFM) image of a cross section of the lens demonstrating the change in material properties from the
core to the surface. With a center thickness of 90 mi36
•
CONTACT LENS SPECTRUM/SPECIAL EDITION 2013
Three primary approaches have been suggested to
enhance comfortable wear of contact lenses: providing a low modulus hydrogel surface, maintaining
wettability throughout the day, and minimizing the
friction of the lid crossing the front lens surface.
The water gradient of Dailies Total1 lenses address
the modulus challenge by providing a soft, cushioning
layer on the outer surface of lens. This can be measured using an AFM modulus scan (Figure 3).5
In addition to the modulus gradient observed in the
AFM scan, there is an ultra-soft surface gel on the
outermost surface of the lens. The high water content
at the surface provides an extremely wettable interface
with the tear film. Measurements by Menzies and
Jones12 showed Dailies Total1 lenses had lower advancing and receding contact angles, as measured by a
sessile drop, than other tested daily disposable contact
lenses with the exception of nelfilcon A (Dailies Aqua
Comfort Plus contact lenses).
Wettability is only one measure of ways to help
www.clspectrum.com
MATERIALS
T a b l e
1
Comparison of Oxygen Permeability and Transmissibility
of Daily Disposable Lens Materials
Lens Material
Dk
Delefilcon A (Dailies Total1 contact lenses, Alcon)
Narafilcon A (Acuvue TruEye, Johnson & Johnson Vision Care – not available in US)
Narafilcon B (US version Acuvue TruEye, Johnson & Johnson Vision Care)
Etafilcon A(1-Day Acuvue Moist, Johnson & Johnson Vision Care)
Omafilcon A (Proclear 1 Day, CooperVision)
Nesofilcon A (Biotrue, Bausch + Lomb)
Dk/t**
140*
100
55
28
33
42***
156
118
65
33
36
42
*Alcon data on File 2010
**Dk/t calculated using manufacturer’s published center thickness for -3.00 diopter lenses when available. Others as published in Tyler’s Quarterly
***Data from FDA 510(k) K113703 Summary June 6, 2012
T a b l e
2
Comparison of Ocular Physiology* and Surface Appearance of
Two Silicone Hydrogel Daily Disposable Lenses and Dailies Total1
Daily Disposable Lenses with a Water Gradient Surface.
Dailies Total1
Contact lenses
(delefilcon A)
Corneal Staining
(0-10,000)
25+54
Conjunctival Staining
(0-100)
4+ 5
PL-NIBUT (seconds)
5.7
Graded wettability compared to
Dailies Total1 lenses
Difference in observed deposition
compared to Dailies Total1 lenses
Clariti 1-Day
Contact lens
(7ettab II 3)
p value
compared
to Dailies
Total1
lenses
Acuvue TruEye
Contact lenses
(narafilcon A)
p value
compared
to Dailies
Total1
lenses
38+ 70
p<0.01
74+ 117
p<0.01
30+ 12
4.7
p<0.01
p<0.01
10+ 8
4.7
No difference
p<0.01
.27
p<0.01
.34
p<0.01
.31
p<0.01
.13
p<0.01
*Mean plus/minus standard deviation
keep contact lenses comfortable. Brennan reported
that lubricity as measured by coefficient of friction is
highly correlated to comfort (r=0.90, p<0.01).13 Korb
and colleagues14 reported that there is a correlation
(p<0.00001) between lid wiper epitheliopathy and dryness symptoms associated with wear of contact lenses.
In studies of 105 symtomatic and asymptomatic lens
wearers, Korb and colleagues14 found 80% of symptomatic patients showed the presence of lid wiper staining compared to 13% of asymptomatic patients within
the first 4 hours of wear.
The novel water gradient surface of the Dailies
Total1 lenses provides a highly lubricious surface.
Contact lenses can provide hydrodynamic lubrication
during the fastest part of a blink as the tear film is
maintained between a contact lens and the eyelid. At
www.clspectrum.com
lower ocular movement speeds, however, a contact
lens is in direct contact with the ocular tissues resulting in much higher friction. The soft, high water surface of the Dailies Total1 lenses acts as a boundary
lubricant during these low speed ocular movements
providing excellent lubricity (low coefficient of friction). Measurements by Sawyer and co-workers 15
found that the coefficient of friction of Dailies Total1
lenses was comparable to or even lower than the coefficient of friction of epithelial cells. Additional qualitative and quantitative methods have been used to
estimate the lubricity (or its inverse the coefficient of
friction) and have demonstrated the highly lubricious
nature of the Dailies Total1 lenses.16 When measuring
the lubricity or friction of Dailies Total1 lenses it is
important to utilize pressures similar to those found in
CONTACT LENS SPECTRUM/SPECIAL EDITION 2013 •
37
MATERIALS
lenses and two competitive silicone hydrogel daily disposable lenses. While the other daily disposable lens
tested were acceptable, Dailies Total1 lenses showed
the least impact on ocular physiology and the least
change in lens surface appearance when evaluated after
8 hours of wear. The results are shown in Table 2.
In a separate report by Varikooty and colleagues,19
the subjective comfort of 53 enrolled symptomatic patients from this study was evaluated. The comfort was
measured at 4, 8 and 12 hours. At each time point
Dailies Total1 lenses was numerically superior to other
silicone hydrogel daily disposable contact lenses.
Conclusion
Modulus shown as the average of 20 linear scans from core to surface (AFM modulus scan-excludes outer
0.5 microns); Alcon data on file 2011.
Figure 3. Modulus comparison of a cross section of Dailies
Total1 contact lenses.
the eye (<7 kPa) because the surface of the lenses is so
soft that higher pressures could actually crush the surface giving erroneous test results.17
Of course the presence of a water gradient, high
oxygen permeability, low surface modulus, enhanced
surface wettability and low friction/high lubricity are
only really meaningful if they impact clinical performance. Keir and colleagues18 reported recently on a
clinical trial with 104 subjects using Dailies Total1
Dailies Total1 lenses provide a new concept in
contact lenses combining the benefit of a high permeability oxygen silicone hydrogel core and a water
gradient transition from the low water silicone hydrogel core to a high water content surface. This
new technology is made possible by the next generation of Alcon’s patented LightStream Lens Technology. The high water surface provides a low modulus,
highly wettable and lubricious surface. This revolutionary technology does not fit the current classification approaches for either the conventional
hydrophilic lens materials or the biphasic silicone
hydrogels, and stand alone as a novel approach to
contact lens chemistry. CLS
References
1. FDA Premarket Notification (510(k)) Guidance for Daily Wear Contact Lenses, May 12, 1994:p24-25.
2. Nichols JJ, Contact Lenses 2011. Contact Lens Spectrum, January 2012;
27:20-25.
3. Morgan PB, Woods CA, Tranoudis IA, et al. International Contact
Lens Prescribing in 2011. Contact Lens Spectrum, January 2012; 27:25-31.
4. ISO 18369-1:2006/Amd 1:2009(E) Ophthalmic Optics-Contact Lenses
Part 1. Vocabulary, Classification System and Recommendations for
Labelling Specifications.
5. Pruitt JP, Yongxing Qui, Thekeli S, Hart R. Surface characterization of
a water gradient silicone hydrogel contact lens (delefilcon A). Invest Ophthalmol Vis Sci 2012; 53: e-abstract 6107.
6. Thekveli S, Qui Y, Kapoor Y, et al. Structure property relationship of
delefilcon A lenses. Poster 41 presented at BCLA 2012.
7. Rumpakis JMB. New data on contact lens dropouts: An international
perspective. Review of Optometry 2010;147(11):37-42.
8. Weed K, Fonn D, Potvin R. Discontinuation of contact lens wear.
Optom Vis Sci 1993;70:140.8.
9. Pritchard N, Fonn D, Brazeau D. Discontinuation of contact lens wear:
a survey. Int Contact Lens Clin 1999;26:157-162.
10. Richdale K, Sinnott LT, Skadahl E, Nichols JJ. Frequency of and factors associated with contact lens dissatisfaction and discontinuation.
Cornea 2007;26:168-74.
11. Young G, Veys J, Pritchard N, Coleman S. A multi-centre study of
lapsed contact lens wearers. Ophthalmic Physiol Opt 2002;22(6):516-527.
38
•
CONTACT LENS SPECTRUM/SPECIAL EDITION 2013
12. Menzies K, Jones L. Sessile drop contact angle analysis of hydrogel and
silicone hydrogel daily disposable and frequent replacement contact
lenses. Cont Lens Ant Eye 2012; BCLA abstract 35.
13. Brennan NA. Contact lens-based correlates of soft lens wearing comfort brennan na, contact lens-based correlates of soft lens wearing comfort. Optom Vis Sci 2009;86:E-abstract 90957.
14. Korb DR, Greiner JV, Herman JP, et al. Lid wiper epitheliopathy and
dry eye symptoms in contact lens wearers. CLAO 2002;28(4):211-216.
15. Sawyer WG, Dunn AC, Uruena JM, Ketelsen HA. Robust contact
lens lubricity using surface gels. Invest Ophthalmol Vis Sci 2012;53:
e-abstract 6095.
16. Tucker RC, Quinter B, Patel D, et al. Qualitative and quantitative lubricity of experimental contact lenses. Invest Ophthalmol Vis Sci
2012;53:e-abstract 914.
17. Angelini TE, Dunn AC, Uruena JM, Ketelson H, Sawyer WG. Stress
induced frictional transitions in cross-linked surface gels. Invest Ophthalmol Vis Sci 2012;53(E-abstract 6113).
18. Keir NJ, Varikooty J, Richter D. Evaluation of lens surface appearance
and ocular physiology with three silicone hydrogel daily disposables.
Cont Lens Ant Eye 2012; BCLA abstract 15.
19. Varikooty J, Keir N, Richter D, et al. Subjective comfort with three silicone hydrogel daily disposables in symptomatic contact lens wearers.
Cont Lens Ant Eye 2012; BCLA abstract 21.
www.clspectrum.com
Contact Lens Spectrum
STABILITY
IS THE CORE OF OUR DESIGN
R
ENT
PLA SM
A S URFA CE T
ECH
NO
LO
GY
2/13
PE
N
MA
≤5º OF OSCILL ATION
9
STABILIZED HERE
3
8
4
STABILIZED HERE
PRECISION BALANCE
8|4 TM DESIGN
6
8|4™
PRECISION BALANCE
1
SCRIBE MARKS AT 3, 6, AND 9 O’CLOCK
2,3
4
AIR OPTIX® for Astigmatism
myalcon.com
®
Engineered for sustained performance
Important information for AIR OPTIX® for Astigmatism (lotrafilcon B) contact lenses:
References: 1.
2.
3.
Optom Vis Sci
4.
© 2013 Novartis 12/12 AOT13001JAD
80924 AOT13001JAD CLS.indd 1
1/14/13 4:23 PM
NEW PRODUCT
The Development of
Dailies Total1 Water
Gradient Contact Lenses
Research led to a departure from using a single bulk
material for the whole lens.
By John Pruitt, PhD
and Erich Bauman, OD, FAAO
T
Dr. Pruitt is Project Head,
Biocompatibility Projects for
Alcon Vision Care R&D. He
received his PhD in Chemical
Engineering from Brigham
Young University.
Dr. Bauman is project head
for Dailies Total1 projects
within Vision Care Research
& Development at Alcon
Laboratories, Inc. He received
his doctor of optometry
degree with honors from the
Southern California College
of Optometry in 1982 and
an MBA from Coles College
of Business in 2001.
40
•
he development of the
delefilcon A lens material
that makes up Dailies
Total1 contact lenses
began more than 10 years
ago and involved a dedicated multi-national
team of scientists, engineers and
clinicians. Early in the development, the team had many intense
discussions about what lens
properties should be targeted in
order to create the most comfortable contact lens possible.
The team quickly recognized the
many limitations and trade-offs
inherent in relying on a single
bulk material.
By way of analogy, it is known that
the cornea is comprised of different
tissue layers, each with their own
unique anatomical structure and physiological function. When integrated
into one organ, these layers perform
multiple functions, for example, light
refraction, mechanical support andphysiologic protection of the eye.
When selecting a target water content, the R&D team recognized from
our experience with silicone hydrogel
CONTACT LENS SPECTRUM/SPECIAL EDITION 2013
materials that a low water content
material with high levels of silicone
would provide excellent oxygen transmissibility, good handling characteristics and resistance to dehydration.
Conversely, from our experience with
The surface coefficient
of friction, or lubricity,
has been shown to have
a high correlation with
lens comfort scores.
(non-silicone) traditional hydrogel
materials, we knew that extremely
high water content materials without
silicone could provide excellent wettability, lubricity, and resistance to lipid
fouling.
The R&D team recognized that an
extremely low modulus may make a
lens easier to fit and help provide
improved comfort but at the cost of
decreased lens handling performance.
There also seemed to be a limit to
www.clspectrum.com
NEW PRODUCT
Figure 1. Cross section illustration of Dailies Total1 water gradient contact lens
how soft one can make a lens material. The modulus
of corneal epithelial cells1 is less than 0.02 MPa and
it seemed impossible to make a contact lens material
as soft as that without it simply falling apart.
Following the paradigm of using multiple materials
as in the cornea, we realized that some of these
properties, such as oxygen transmissibility and lens
handling, could be controlled by a lens ‘core’ material
while other properties like wettability and lubricity
were only important at the surface. A lens with only
a single water content, modulus or chemistry
would always entail some level of compromise.
The team arrived at the question: “why
should patients have to settle for the same
water content at the core and surface, or
indeed the same material chemistry at the core
and surface of a lens?” This led to a radical
departure from single bulk material thinking
and formed the basis for the development of
the delefilcon A water gradient lens material.
breathable silicone hydrogel material at the core to a
non-silicone hydrophilic polymer structure at the
surface (Figure 1). This enables a lens with a Dk/t of
156 (at the center of a -3.00D lens) combined with a
surface-water content of over 80%,1 as seen in Figure 2.
A gradient occurs between the two areas in which the
water content rapidly increases and the material shifts
from a silicone-rich core material to an essentially
silicone-free surface gel.2 This surface material forms
an ultrasoft surface gel and makes up about 10% of the
Revolutionary Change
lens thickness. While the average water content of the
ultrasoft surface gel exceeds 80%, the water gradient
structure allows the water content to approach almost
100% at the outermost surface of the lens.3
Several laboratory techniques have measured this
change in lens material properties including Atomic
Force Microscopy (AFM), Neutron Reflectometry,
and Fluorescent Laser Confocal Microscopy.2 These
A measurable change can
be demonstrated in the lens
material, the water content
and the modulus of delefilcon A
from core to surface.
A measurable change can be demonstrated in the lens
material, the water content and the modulus of delefilcon A from core to surface. This represents the firstever water gradient contact lens designed to feature an
increase from 33% to more than 80% water content
from core to surface. To enable this water gradient,
the delefilcon A lens material transitions from a highly
www.clspectrum.com
CONTACT LENS SPECTRUM/SPECIAL EDITION 2013 •
41
NEW PRODUCT
* Dk/t at center of -3.00D lens based on manufacturer-published values.
** Core water content and lens overall water content are both 33% ± 2%.
† Water content for competitor lenses are manufacturer-published lens overall water contents.
Figure 2. The delefilcon A lens material transitions from a highly breathable silicone hydrogel material at the core to a
non-silicone hydrophilic polymer structure at the surface, allowing for a lens with a Dk/t of 156 (at the center of a -3.00D
lens) combined with a surface-water content of more than 80 percent.
methods demonstrate the gradient in modulus and
other lens properties across the lens cross section,
not seen in other lens materials.
The modulus of the lenses also changes with the
material becoming much softer at the surface of the
lens with the outer surface having a compression
modulus of only about 0.025 MPa.4 The modulus of
the lens core is maintained at 0.7 MPa for excellent
insertion handling. The surface modulus of delefilcon A is almost as soft as the corneal epithelial
cells1,5 yet this ultrasoft surface gel is able to maintain
its integrity because it is supported by the lens core
material. In a similar manner the ultrasoft corneal
epithelial cells are supported by collagen fibrils, giving the cornea an overall bulk modulus that is much
higher than the modulus of the individual cells.
Highly Breathable Daily Disposable Lens
Why do we need such a high Dk/t for a daily disposable contact lens? There are several factors to consider. Stated Dk/t values (and even theoretical flux or
equivalent oxygen estimations) are normally provided only for the center of a -3.00D lens. The greater
peripheral lens thickness means oxygen transmissi42
•
CONTACT LENS SPECTRUM/SPECIAL EDITION 2013
bility is lower with minus powers, but in plus powers,
the central oxygen transmission values will be lower
than the stated value for -3.00D. Figure 3 illustrates
this with the color oxygen maps across the whole
lens in different materials and powers. The blue end
of the spectrum is used to indicate high Dk/t and red
shows areas of lower Dk/t. It has become apparent
that a single Dk/t value isn’t sufficient to completely
characterize the oxygen transmission in contact
lenses. Furthermore, the published Dk/t values for
the lenses only represent a small portion at the
center of a -3.00D lens. The peripheral oxygen
transmissibility is generally much lower as seen in
the colored maps. Research demonstrates that
peripheral oxygen transmission is equally important
to ocular health as that in the center.6 In addition,
different patients have different oxygen demands,
some of which may not be predictable during a
routine examination, even when using a slit lamp.7
Thus, starting with the highest available central Dk/t
value is in the best way to avoid hypoxic concerns
and meet the needs of various patient lifestyles.
Oxygen transmissibility in delefilcon is largely determined by the core of the lens because it comprises the
www.clspectrum.com
NEW PRODUCT
Note: Dk/t at center of -3.00D lens and Dk are based on manufacturer-published values.
Figure 3. Oxygen transmissibility in delefilcon is largely determined by the core of the lens because it comprises the
majority of the lens thickness.
majority of the lens thickness. Of particular interest are
the unique properties at the surface of the lens, because
these are key to a comfortable lens-wearing experience.
The Importance of Surface Lubricity
The comfort of a contact lens may be influenced by
many factors ranging from the modulus of the material, lens thickness, and water content to lens design
and parameters. The surface coefficient of friction, or
lubricity,8 has been shown to have a high correlation
with lens comfort scores. Lubricity is the inverse of
friction and, for a contact lens, is described as how
easily the components of the ocular surface, such as
the palpebral conjunctiva, can slide across the lens
surface. We blink about 14000 times per day.9 With
each blink, the superior lid has to slide down, then
back up over the lens surface. As such, it makes sense
that lubricity is highly predictive of lens comfort. Lubricity can be detected with the fingers as a slippery
feeling and it can be measured by using either an inclined plane or a micro tribometer.10 Regardless of
www.clspectrum.com
the method used to measure lubricity, it is important
that the pressures reflect those found in the ocular
environment — in other words, matching those exerted by the eyelid against the lens on eye). This is especially important when measuring the lubricity of
delefilcon A because the extremely soft water gradient surface structures can be artificially crushed if
measured at pressures that exceed those found in the
eye thereby giving erroneous lubricity results at high
testing pressures.11
Using kinetic coefficient of friction, measured by the
inclined plate method, delefilcon A has been shown to
have extremely low friction (excellent lubricity).5
A new contact lens with different core and surface
properties meant that detailed research was needed
to optimize the chosen design parameters. Numerous studies were conducted to co-optimize the base
curve, diameter and lens design. Ultimately, the
combination of an 8.5mm base curve with a 14.1mm
diameter was selected to give optimal centration and
lens movement. The full technical specifications and
CONTACT LENS SPECTRUM/SPECIAL EDITION 2013 •
43
NEW PRODUCT
range of parameters can be seen in
Table 1.
Exceptional Comfort
Throughout the Day
The outcome of this superior
lubricity is outstanding wearer
comfort through the end of the day.
In a clinical study with 104 subjects,
cumulative comfort scores were superior for Dailies Total1 contact
lenses in comparison with other
silicone hydrogel daily disposable
lenses.12 In a group of 53 symptomatic subjects, 100% of them could
wear Dailies Total1 contact lenses
for at least 8 hours and 85% were
able to wear them up to 12 hours.
In comparison to their habitual
lenses, the majority of the subjects
were able to wear Dailies Total1
contact lenses for clinically significant longer periods of time.13
T a b l e
1
Dailies Total1 Parameters & technical specifications
Material
Surface Water Content (%)
Base Curve (mm)
Center Thickness (mm) (-3.00D)
Core Water Content (%)
Dk/t
Core Modulus (MPa)
Packaging
Diameter (mm)
Handling Tint
Manufacturing
Power Ranges (at launch)
Diopters
The Start of a New Era
Since soft contact lenses were first introduced, there
have been numerous incremental changes to
materials to improve water retention and wearer
comfort. Ciba Vision introduced the first silicone
hydrogel contact lens in 1998, ushering in a new era
in lens material technology that has triggered
extensive steps to improve oxygen transmission for
patients worldwide. The creation of the first water
Delefilcon A
>80%
8.5
0.09
33%
156 @ -3.00D
0.7
5 (trials), 30 pack, 90 pack
14.1
VISITINT lens
Newest generation of LightStream
Technology enables the creation of the
water gradientLenses contain
phosphatidylcholine, an ingredient
also found in natural tears.
-0.50 to -6.00 (in 0.25 steps)
-6.50 to -10.00 (in 0.50 steps)
gradient contact lens, featuring an increase from
33% to over 80% water content from core to
surface, marks the start of yet another new era in
contact lenses, and with it, hope for a new era in
comfort for contact lens wearers around the world. CLS
Editor’s note: A similar article appeared in the April 5, 2013 edition of Optician.
See product instructions for complete wear,
care, and safety information
References
1. Straehla J, Limpoco F, Dolgova N, Keselowsky B, Sawyer
WG. Tribology Letters 2010;38(2):107-113.
2. Thekveli S et al. Structure-property relationship of delefilcon
A lenses. BCLA Annual Clinical Conference, 2012.
3. Angelini TE, Nixon RM, Dunn AC, Uruena JM, Pruitt J,
Sawyer WG. Viscoelasticity and mesh-size at the surface of
hydrogels characterized with microrheology. Invest Oph Vis
Sci 2013;54(E-Abstract 500).
4. Dunn A, Urueña J, Huo Y, Perry S, Angelini T, Sawyer WG.
Lubricity of surface hydrogel layers. Tribology Letters
2013;49(2):371-378.
5. Rudy A, Huo Y, Perry SS, Ketelson H. Surface mechanical
and tribological properties of silicone hydrogels measured by
atomic force microscopy. Invest Oph Vis Sci 2012;53(E-Abstract 6114).
6. Papas E, Willcox M. Reducing the consequences of hypoxia:
the ocular redness response. Contact Lens Spectrum, special
edition 2006; pages 32-37.
7. Bonanno JA, Nyguen T, Biehl T, Soni S. Can variability in
corneal metabolism explain the variability in corneal
44
•
CONTACT LENS SPECTRUM/SPECIAL EDITION 2013
8.
9.
10.
11.
12.
13.
swelling?. Eye Contact Lens 2003;29(1 Suppl):S7-S9;discussion
S26-29, S192-194.
Brennan NA. Contact lens-based correlates of soft lens-wearing comfort. Opt Vis Sci Abstract 90957, November 2009.
Inoue K, Okugawa K, Amano S, et al. Blinking and superficial punctate keratopathy in patients with diabetes mellitus.
Eye (Lond). 2005;19(4):418-421.
Subarraman L, Jones LW. Measuring friction and lubricity
of hydrogel contact lenses – A review. Contact Lens Spectrum;
2013 (in press).
Angelini TE, Dunn AC, Uruena JM, Ketelson H, Sawyer
WG. Stress induced frictional transitions in cross-linked surface gels. Invest Oph Vis Sci 2012;53(E-abstract 6113).
Keir N, Richter D, Varikooty J, Jones L, Woods C, Fonn D.
End of day comfort using a novel cumulative comfort score.
Invest Oph Vis Sci 2012;53(E-Abstract 4728).
Varikooty J, Keir N, Richter D, Jones L, Woods C, Fonn D.
Subjective comfort with three silicone hydrogel daily disposables in symptomatic contact lens wearers. BCLA Annual
Clinical Conference, 2012.
www.clspectrum.com
Contact Lens Spectrum
Some surfaces are worth protecting
5/13
THE OCULAR SURFACE IS ONE.
The SYSTANE® portfolio includes products that are
engineered to protect, preserve and promote a healthy
ocular surface1-5. See eye care through a new lens with
our innovative portfolio of products.
References
1. Christensen MT, Blackie CA, Korb DR, et al. An evaluation of the performance of a novel lubricant eye drop. Poster D692 presented at: The Association for Research in Vision and Ophthalmology Annual Meeting; May 2-6,
2010; Fort Lauderdale, FL. 2. Davitt WF, Bloomenstein M, Christensen M, et al. Efficacy in patients with dry eye after treatment with a new lubricant eye drop formulation. J Ocul Pharmacol Ther. 2010;26(4):347-353.
3. Data on file, Alcon. 4. Wojtowica JC., et al. Pilot, Prospective, Randomized, Double-masked, Placebo-controlled Clinical Trial of an Omega-3 Supplement for Dry Eye. Cornea 2011:30(3) 308-314. 5. Geerling G., et al. The
International Workshop on Meibomian Gland Dysfunction: Report of the Subcommittee on Management and Treatment of Meibomian Gland Dysfunction. IOVS 2011:52(4).
Surface Protection and More
© 2012 Novartis 10/12 SYS13100JAD
82414 SYS13100JAD CLS.indd 1
5/22/13 3:27 PM
ROUNDTABLE DISCUSSION
Groundbreaking
Technology Debuts in
Daily Disposable Market
Panelists discuss a unique new lens that has surprising
characteristics designed to defeat discomfort.
Dr. Eiden: Today, we’ll share our
experiences with what we believe is a
revolutionary new contact lens technology. The Alcon Dailies Total1
lens was designed to address some of
the key challenges we still face in daily
practice in a way that we haven’t been
able to do before, relating to all-day
comfort, visual performance and
breathability. Let’s begin by discussing some of those challenges.
Number One Complaint
S. Barry Eiden, OD, FAAO
(moderator)
Mile Brujic, OD
April Jasper, OD, FAAO
Jordan Kassalow, OD
Kelly Nichols, OD, MPH, PhD,
FAAO
John L. Schachet, OD
This roundtable discussion
was held during SECO 2013.
For complete biographies
and disclosures, please see
page 52.
46
•
Dr. Eiden: Dr. Brujic, do you always know when patients are dissatisfied with their habitual contact lenses?
Dr. Brujic: I see two types of challenging patients. The first is the noncomplaining patient, and the second is
the habitually complaining patient.
The non-complainers seem to have
no problems, but often, I think
they’re reluctant to complain, because
they’re concerned they’ll have to stop
wearing contact lenses.
Dr. Eiden: How do you help these
patients open up?
Dr. Brujic: I ask them to rank the
quality of their vision and the comfort
of their lenses, each on a scale from
0 to 10. Many people who tell me
their comfort is “fine” or “great” give
CONTACT LENS SPECTRUM/SPECIAL EDITION 2013
their lenses a grade that is less than
the 10 I’d expect for comfort that is
“fine.” This is a huge opportunity for
me to introduce new technologies to
these patients, as well as to patients
who do verbalize their complaints.
Dr. Eiden: Dr. Jasper, do you find
the same thing happening in your
practice? Do you see it as an opportunity to make changes for your patients?
Dr. Jasper: Absolutely. The most
common complaint I hear is that patients can’t wear their lenses as long
as they want to during the day. When
a patient tells me this, it’s my job to
find out why. Typically, it’s because
the lenses are not comfortable, or the
patient’s lenses feel dry. Another challenge is the patients who tell us what
they think we want to hear just to
make us happy.
Dr. Eiden: What do you do when
you suspect a patient is just telling
you what you want to hear?
Dr. Jasper: I help them get past
that by rewording my questions. I
may ask, “What’s the longest amount
of time you can wear your lenses
comfortably during the day?” or
“How often do you switch to your
eyeglasses before the end of the day?”
www.clspectrum.com
ROUNDTABLE DISCUSSION
Start With Staff to Build Excitement
D
r. Eiden: Educating our staff members about new technology is critical to be successful in bringing
new technologies to our patients. How have you educated your staff about Dailies Total1 technology?
Dr. Brujic: The best way to educate your staff is to have those who are contact lens wearers try the
lenses, so they can share their excitement and their experiences.
Dr. Jasper: After you’ve explained the benefits of the lens, how amazing it is and how fortunate we
are to have it available to us, then watch to see to whom they recommend the lens first. Usually, it’s
their friends and family. That tells you they believe in it. They’ve tried it, and they want the people they
love most to be the first to have it.
Dr. Kassalow: I’m fortunate to have staff members who have been with my practice for many years.
They know most of my patients, and my patients trust them. I’ve noticed an interesting phenomenon
with the Dailies Total1 lenses. In the past, staff members might talk about their cool eyeglasses, but they
would never talk about their contact lenses. Now, patients are asking for Dailies Total1 lenses based on
the enthusiasm of the staff members who are wearing them. Making new lens technology an emotional
experience speaks volumes, particularly when the experience is relayed by someone who is trusted, such
as staff members.
Dr. Eiden: I agree wholeheartedly that the experience is where it’s at. I do think, however, that sharing the science is equally important. Our technical staff always want to know the science behind things.
So we include it as part of our office meetings. Our staff understands the technology and has bought into
this concept.
Dr. Eiden: Dr. Nichols, what questions do you
ask your patients to uncover any comfort issues?
Dr. Nichols: I always ask patients how many
hours a day they wear their lenses, how many hours
they want to wear them and what things they’ve tried
to eliminate some of their discomfort. In my practice, I see patients who are having more significant
issues. Many of these patients are former contact lens
wearers who really want to wear them again. I think
sometimes we’re quick to say, “You’re done with
contact lenses,” instead of trying something new.
When patients start to drop out in their 30s or 40s,
we need to try to figure out if we can do something
to keep them comfortable in lenses, because they
want to wear them.
Dr. Eiden: Other issues that concern us in terms
of contact lens performance include ocular health
response and visual response. Dr. Schachet, how important are these aspects in comparison to comfort
issues?
Dr. Schachet: They’re all important and interrelated. Most of my patients who have discomfort
have either a dryness problem, which can be accompanied by fluctuating vision, or they’re not using the
ideal lens care solution for their lenses. So, whether
we’re talking about initial comfort or end-of-day
comfort, I look at those two things primarily before
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looking at anything else. We have to be proactive,
and we need to listen. When we listen carefully to
what patients say, the problem often becomes apparent even before we go to our instrumentation.
Unmet Needs in Daily Disposables
Dr. Eiden: Dr. Kassalow, you fit a significant
number of daily disposable lenses. What impact has
this modality had on your practice?
Dr. Kassalow: The four areas I always focus on
when discussing contact lenses with patients are
comfort, convenience, vision and health. Daily disposable lenses hit each of those areas square on.
From my experience, daily disposable lenses are the
most comfortable modality, and patients who wear
them are my happiest group of patients. When I see
a patient who’s wearing daily disposable lenses, I
know that 9 out of 10 times, it will be a relatively
easy office visit.
Dr. Eiden: How do they rate their vision?
Dr. Kassalow: They’re just as happy with their
vision, because every day, they have a fresh lens.
The lens is wet and clean, and they like that. They
also love the convenience. They don’t have to use
care solutions and feel like a chemist every night.
Dr. Eiden: And health?
Dr. Kassalow: My patients and I both love the
CONTACT LENS SPECTRUM/SPECIAL EDITION 2013 •
47
ROUNDTABLE DISCUSSION
fact that daily disposable lenses are a healthy option.
The modality has been a fantastic practice-builder.
Overall, my patients are happier than they were
before they started wearing daily disposables.
Dr. Eiden: Where do you see opportunity for advancement in daily disposable lenses?
Dr. Kassalow: Despite having many daily disposable lenses, we still have a group of patients who
aren’t comfortable wearing them, so I’m excited
about the Dailies Total1 lens and the advent of this
new technology. I think it will fundamentally shift
the comfort curve.
Dr. Jasper: I think it all comes back to the one
thing we’ve discussed so far. Discomfort is still an issue for some patients. I still have patients who tell
me they can wear their lenses for only 6 hours a day.
New and Unique Properties
Dr. Eiden: Dailies Total1 technology is truly revolutionary, because it’s totally different from any
other material. It’s the first water gradient silicone
hydrogel lens. Dr. Brujic, what is meant by water
gradient and how is this lens different from any other HEMA or silicone hydrogel lens?
Dr. Brujic: Dailies Total1 lenses are manufactured in a new silicone hydrogel material called delefilcon A, which is designed to enable a gradual
transition from 33 percent water at the core of the
lens to over 80 percent at its surface. Amazingly, this
happens in a 6-micron space.
Dr. Nichols: All contact lenses aim to simulate the
ocular surface and conform to the environment of the
tears in a way that enhances the tears or at least doesn’t
harm anything about the tears — almost as though the
lens isn’t there. In short, the Nirvana of contact lens
wear is to have no lens awareness. A number of studies
have shown that changes to the ocular surface tissues
are highly associated with symptomatic contact lens
patients.1,2 This lens has a surface that mimics the natural hydrophilic ocular surface.
Dr. Eiden: Dr. Kassalow, how do you explain the
concept of lubricity to your patients?
Dr. Kassalow: I always talk about lubricity as a
feature of the lens. Different patients have appetites
for different amounts of information, so to some patients, I say, “This is the single best, most comfortable lens I’ve worked with in my 25-year career.
Let’s try it,” and they say, “Great. Let’s do it.” Others may tell me they’re comfortable with their current lenses and ask for more information. For them,
I focus on how lubricity equates to comfort.
Dr. Schachet: What’s nice about this lens is that
the lid has no effect on it because it virtually glides
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CONTACT LENS SPECTRUM/SPECIAL EDITION 2013
over water. That’s another point that makes it easier
for patients to understand.
Dr. Eiden: Handling a contact lens can be a challenge for some patients. We always talk about the
convenience of daily disposables, but I’ve had patients reject them simply because they were difficult
to handle. Dr. Jasper, tell us about the modulus gradient and how that influences lens handling.
Dr. Jasper: Dailies Total1 lenses have a lowmodulus surface, which enhances comfort, and a
high modulus core, which facilitates ease of handling. I proactively explain to patients how I want
them to apply and remove these lenses. I think the
most noteworthy characteristic, especially for patients who have worn lenses all their lives, is that after applying the lens, they hardly know it’s there —
except that they can see. Lens removal may be somewhat challenging for some patients. I instruct them
to be sure their hands are thoroughly dry before they
remove the lenses.
Dr. Eiden: The same attribute that makes the
lens so lubricious makes it somewhat difficult to remove if your fingers are wet, because it just slides
right over the lens surface.
Dr. Brujic: I refit a patient who’d been wearing
another brand of daily disposable lenses into Dailies
Total1 lenses. When he tried to remove them by
pinching them off of his cornea, he had some trouble. After I explained how to remove these lenses —
the slide-and-pinch technique — and that he was
having trouble because of how slick the lens surface
is, he suddenly said, “Wow, now I really understand
why this is such a comfortable lens.”
Highest Dk/t in a Daily Disposable
Dr. Eiden: With a Dk/t of 156 (@–3.00D),
Dailies Total1 lenses have the highest oxygen transmissibility of any daily disposable lens. Assuming
perfect compliance, do you think the cornea needs
this much oxygen?
Dr. Schachet: Each patient’s requirement for oxygen is different, but I don’t think there’s anything
wrong with aiming for high oxygen transmissibility.
Dr. Jasper: We don’t know every reason why
people drop out of contact lenses. People say discomfort and dryness, but it seems to me if you provide them with the most oxygen throughout a
lifetime of contact lens wear, they’ll have fewer
problems. As Dr. Schachet mentioned, we don’t
know what each individual’s unique oxygen need is.
It depends on their lens, where they live, what they
do, and so on, so going high in my mind is not a bad
thing.
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ROUNDTABLE DISCUSSION
Dr. Brujic: It used to be a more relevant argument when we were trying to decide between oxygen transmissibility and wettability. With the
Dailies Total1 lens technology, we don’t have to
give up either.
Dr. Jasper: I tell my patients, “I want to give you
a contact lens that is like having nothing on your
eye.” In other words, we want a lens that’s the least
like a lens, and I would hope that every company
that works with contact lenses would strive to do
that for our patients.
Dr. Eiden: That is a powerful statement. Why do
we put a contact lens on anybody’s eye? To help them
see better. So, the more that it’s like nothing, other
than vision correction, the better it is for our patients.
Personal Experiences
Dr. Eiden: We’ve discussed many of the attributes that make Dailies Total1 unique and exciting.
Most of us have had the opportunity to wear these
lenses. I’d like to get your personal feedback on
wearing these lenses.
Dr. Nichols: I’m the perfect example of a patient
looking for a more comfortable daily disposable lens.
I’m probably always going to have some comfort issues, because I work long hours late at night on the
computer. I’ve worn Dailies Total1 lenses for about
6 months, and I can wear these lenses longer and
more comfortably than any other daily disposable
lens that I’ve worn.
Dr. Schachet: Overwhelmingly, this is the most
comfortable lens I’ve ever had on my eye, and that is
directly attributable to the water gradient. When it’s
on the eye, you don’t even know you’re wearing a contact lens. It’s the most incredible lens-wearing experience I’ve had in all the years I’ve been practicing.
Dr. Nichols: Our patients deserve the chance to
try these lenses. I don’t think people recognize
they’re uncomfortable until they experience comfortable.
Dr. Eiden: More than a year ago, I had my first
exposure to this technology in Europe. At the end of
my first day wearing the lens — we sat down to dinner at about 11:00 p.m. — I realized I still had the
lenses on, but I didn’t feel them. That’s never happened to me before. Usually after 3 or 4 hours, I
have to peel the lenses off of my eyes.
We’ve recounted our personal experiences.
Now, let’s discuss how our patients are reacting to
Dailies Total1 lenses.
Patients’ Experiences
Dr. Brujic: One of the high moments for me as a
www.clspectrum.com
clinician is putting lenses on eyes at the beginning of
lens wear, because that sets a precedent in a patient’s
mind of how that lens will perform. The beautiful
thing about the Dailies Total1 lens is its excellent
initial comfort.
Dr. Eiden: Dr. Jasper, you had an anecdote you
wanted to share.
Dr. Jasper: One of my patients, a teenager, was
wearing another lens, apparently successfully, but I
wanted her to try the Dailies Total1 lenses. As soon
as she put them on her eyes, she said, “Oh my goodness. I had no idea my contacts were supposed to feel
like this.” She didn’t really understand how to answer my questions about comfort, but once she experienced the “no-lens” feeling, she understood what it
was really supposed to be like.
Dr. Kassalow: When a patient comes in happy
and with the attitude “if it ain’t broke, don’t fix it,”
it’s easy for us to buy into that, because it makes our
day go more smoothly. When contemplating a
change for one of these patients, I sometimes ask
myself, “Am I setting myself up for headaches? Am I
slowing down my day? Am I inconveniencing the patient?” Sometimes, my inclination is to just leave
well enough alone. Every person on whom I’ve tried
the Dailies Total1 lens has had a positive experience.
It doesn’t create that backlash of having to try a different lens and repeat the cycle. That’s an important
dynamic in my practice that will prompt me reach
for this lens frequently. It’s not creating more work
for me. It’s making my day go faster, and I’m putting
patients into a premium product.
Dr. Nichols: I like the idea that it streamlines
your process, because you’re not trying a lens that
might be uncomfortable. You’re confident this lens
will be successful.
Dr. Eiden: We have to constantly present new
technologies and reinvent ourselves to give patients a
reason to come to see us regularly. For that reason,
I’ve presented these lenses to happy patients who apparently have no problems. I say, “Yes, I know everything is great, and if you want to continue with your
current lenses, you can, but I want you to test-drive
some new technology.” I’ve found that these patients
do see an improvement. It may not be as dramatic as
the improvement seen by symptomatic patients, but
they still see a bump up.
Dr. Brujic: That’s the true test of good technology: taking an asymptomatic patient, someone who
has no problems, and improving his experience. This
lens is giving us the ability to do just that.
Dr. Kassalow: I’ve definitely seen that happen.
Several hundred of our patients are wearing a com-
CONTACT LENS SPECTRUM/SPECIAL EDITION 2013 •
49
ROUNDTABLE DISCUSSION
petitor’s product that is being discontinued. We
Dr. Kassalow: I will clearly position Dailies Tomailed them information, letting them know the
tal1 contact lenses as a go-to, first-reach lens. It is a
product would no longer be available, and we invited
premium lens with a premium-lens price, so some
them to come in and try the Dailies Total1 lens.
people may push back because of the cost and stay
Four out of five of the people who have tried this
with products that are less expensive. In those cases,
lens so far have said, “Wow, thanks, doc. This is betI’ll use it as a problem-solver when appropriate.
ter than I knew I could have.”
Dr. Eiden: How have patients responded so far to
Dr. Schachet: Another patient whom we haven’t
the higher cost of this new technology?
discussed is the new contact lens wearer. Anyone
Dr. Schachet: Reactions have been mixed so
who’s never worn a contact lens has an opinion of
far. It wouldn’t be fair to say it has been accepted
how it will feel on their eyes. When new wearers try
overwhelmingly; however, I recently had an inDailies Total1 lenses, they’re amazed, because they
teresting case. Some long-time patients came in
don’t even know it’s there.
with their sons, ages 13 and 15 years. They had
Dr. Nichols: That’s a good point. Why not start
been wearing contact lenses, but not very comwith innovative technology rather than “fix” a problem?
fortably. When they tried Dailies Total1 lenses,
Many patients are accustomed to
both boys had an overnew technology in other aspects
whelmingly positive experiof their lives.
ence. This was the first time
Dr. Eiden: That’s an interthey’d been able to wear
esting perspective. We’re “fixcontact lenses all day. I exing” so many of our patients
plained the cost to their parbecause they have contact
ents. I guess they went home
lens-associated problems. This
and thought it over, because
technology takes us to a whole
3 days later, they called and
new level in terms of prevenordered Dailies Total1 lenstion — having patients start
es for both boys.
with a great lens so they can
Dr. Eiden: Practitioners ofstay with it for a long time.
ten wonder: Should we or
Dr. Schachet: Even though
shouldn’t we discuss the cost
this is the closest to a perfect
before the patient experiences
lens we have, we have to rethe lens? I’ve decided I want
member that some patients
my patients to experience the
will have dryness issues. If we
lens first. I do mention the cost
don’t address that, they won’t
is a bit higher, but I tell pabe able to wear the lenses all
tients, “I don’t want to talk
day.
about the cost now, because I
Dr. Kassalow: That’s a
don’t want that to influence
great point. Even though we
how you respond to this lens. I
all believe this technology is a
— John L. Schachet,OD just want you to experience it.
quantum leap forward, we still
If your experience is as positive
need to assess issues that could
as I expect it to be, then we’ll
lead to contact lens-associated dryness.
have that conversation. You can decide if the value is
Dr. Nichols: I agree. When there’s an underlying
worth the price.”
condition, a lens can’t make that go away. We need
Dr. Jasper: I think patients hear “new technoloto evaluate the ocular surface and lids at every visit
gy” and “innovative contact lens,” and they know it
and manage the findings appropriately, even for a
will cost more. I’m okay with that. I’m not going to
patient who says everything is “fine.”
prejudge a patient’s ability or willingness to pay for a
premium product. Those of us who have opticals,
Value Versus Cost
encourage our staff to present the best frames to
Dr. Eiden: From my perspective, Dailies Total1
everybody, so why would we not present the best
lenses are for everybody whose prescription fits the
medical device to everybody. In the end, patients
parameters. Do you agree? Will this lens be a probknow I did not prejudge them, and I treated them
lem-solver or a go-to lens in your practice?
like my best friend and my family.
If you design your
marketing properly
and let people
know this truly is a
revolutionary new
contact lens, there’s
absolutely nothing
like it anywhere in the
world, I think you’ll have
quite a few people
coming in to try it.
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CONTACT LENS SPECTRUM/SPECIAL EDITION 2013
www.clspectrum.com
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5/22/13 3:28 PM
ROUNDTABLE DISCUSSION
Groundbreaking Technology
Dr. Eiden: What does the introduction of Dailies
Total1 lenses mean to you and your practice?
Dr. Nichols: If everyone’s experience is similar to
my own with this lens — being able to wear it comfortably longer than any other daily lens, having
minimal lens awareness, yet maintaining good quality vision — then this technology is going to impact
the daily market. I think it could revolutionize how
we think about the technology behind daily disposable contact lenses, and how we select lens options
for patients, including patients with comfort issues.
Dr. Schachet: This is a unique lens that should
be in a category all alone. There isn’t anything like it
anywhere. When my patients try it, I simply say, “If
this lens isn’t the most comfortable lens you’ve ever
put on, I’d like to hear why.”
Dr. Kassalow: We’ve learned that almost 50 percent of people who stop contact lens wear do so because of discomfort issues,3 and I can’t assume that
my practice is any different. If we can reduce that
number in our practices, it will have a ripple effect
and help us grow exponentially. I think it’s going to
have a huge impact on my practice, because fewer
patients will leave contact lens wear.
Dr. Brujic: We’re taking comfort to the next level with this lens, and I think that’s an exciting place
to be, because comfort is an unmet need in our patient populations. We now have this new tool to help
us keep more patients in contact lenses.
Dr. Jasper: I’m excited about this lens, because,
to me, it means I have a slam-dunk, a lens that will
take care of my patients’ needs. I love being able to
tell my patients, “I’m going to give you the best lens
in every category. It’s also going to give you the best
vision.” This lens makes me look good, and it makes
my patients extremely happy.
Dr. Eiden: Dailies Total1 lenses represent
groundbreaking technology that will enable us to address our patients’ comfort and vision needs — the
whole package. I know I speak for the panel when I
say we’re honored to have been part of the initial
group of practitioners to have access to this technology and to experience it. Now, it will be equally as
exciting for us to share it with our colleagues. CLS
See product instructions for complete wear,
care, and safety information
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CONTACT LENS SPECTRUM/SPECIAL EDITION 2013
S. Barry Eiden, OD, FAAO (moderator)
Dr. Eiden is president and medical director of North
Suburban Vision Consultants Ltd. with offices in
Deerfield and Park Ridge, Ill. He reports no financial
disclosures.
Mile Brujic, OD
Dr. Brujic is a partner in Premier Vision Group, a
four-location practice in northwest Ohio. He is a
consultant/advisor to Alcon, Allergan, Nicox,
TelScreen, Transitions, Valeant Pharmaceuticals,
Vmax Vision and Valley Contax. He has received research support
from Alcon and VMax. He has lectured and/or received honoraria
from Alcon, Allergan, Vmax and Valley Contax.
April Jasper, OD, FAAO
Dr. Jasper practices at Advanced Eyecare Specialists
in West Palm Beach, Fla. She is a consultant/advisor
to Alcon, Eyefinity and Marco. She has lectured or received honoraria from Konan and Carl Zeiss Meditec.
Jordan Kassalow, OD
Dr. Kassalow is a partner at Farkas, Kassalow and
Resnick in New York City, N.Y. He reports no financial
disclosures.
Kelly Nichols, OD, MPH, PhD, FAAO, Dipl PH
Dr. Nichols is a FERV Professor at the University of Houston
College of Optometry. Dr. Nichols has stock options in
TearLab. She is a consultant for Alcon, Allergan, Bausch +
Lomb and SarCode. She has received research support
from Alcon, Allergan, SarCode, TearLab and Vistakon.
John L. Schachet, OD
Dr. Schachet is president and CEO of Eyecare Consultants
Vision Source in Englewood, Colo. He is a
consultant/advisor to Alcon and Tear Science. He has
received research support from Alcon. He has lectured
and/or received honoraria from Alcon and CooperVision.
References
1. Best N, Drury L, Wolffsohn JS. Predicting success with silicone-hydrogel contact lenses in new wearers. Cont Lens Anterior Eye March 19, 2013; Epub ahead of print.
2. Situ P, Simpson TL, Jones LW, Fonn D. Effects of silicone
hydrogel contact lens wear on ocular surface sensitivity to tactile, pneumatic mechanical, and chemical stimulation. Invest
Ophthalmol Vis Sci 2010;51(12):6111-6117.
3. Rumpakis J. New data on contact lens dropouts: an international perspective. Rev Optom 2010;147(1):37-42.
www.clspectrum.com
Contact Lens Practice Pearls
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Setting the Stage for Daily
Disposable Contact Lenses
I
t’s easy to say patients will benefit from daily disposable contact lenses, but it’s more difficult to
go out there on a daily basis and discuss this.
Recommending and refitting everyone requires
time and energy from the doctor
and staff. This may be especially
difficult when your practice has a
full schedule. You need a unified
approach to discussing daily
disposable lenses, especially for
patients who present with no
complaints in their current
contact lens prescription.
Break the Ice
If you believe in the daily disposable concept and a patient presents with no complaints and just
wants to renew his contact lens
prescription, consider at least setting the stage for a daily disposable
refit. Use a simple introduction
such as, “Your contact lenses are
working great, but you may want
to consider trying daily disposable
lenses in the future. They offer
excellent vision and are a healthy
option, but with added convenience, because you can throw out
the lenses each night and use new
lenses in the morning. There’s no
need to buy lens care solutions.”
A patient may ask, “but how much
do they cost?,” which leads right
into our pricing strategies.
Pricing Strategies
Proper pricing strategies help
set the stage for daily disposables.
www.clspectrum.com
You can even turn the price
discussion into one easy sentence,
“cost savings, manufacturer mailin rebates and in-office instant
rebates will counteract the price
difference and may even save you
some money when compared to
reusable lenses.” I usually go on
to explain how the cost is virtually
a break-even when you consider
manufacturer rebates and no need
to buy care solutions. And then
there’s the most important commodity — your time in not having to care for contact lenses!
1. Remove pre-conceived obstacles!
First, consider removing your obstacles.
Many eyecare professionals assume patients
don’t want daily disposable contact lenses
because of the presumed cost increase to the
patient. It’s important to understand that
whatever the dollar difference, many patients
are willing to accept it when they recognize
the value of the product. Many of us use these
techniques with regard to optical sales, but
they also apply when discussing daily disposable contact lenses:
Don’t avoid the issue of price: Talk
about the price up front.
Explain the value equation: Daily disposable contact lenses provide improved convenience. Patients don’t have to worry about
the extra costs associated with other modalities, such as buying solutions. If they rip or
tear a lens, they haven’t substantially
increased their costs.
2. Discuss the price after factoring in
rebates and solution cost savings!
Many online stores will quote prices after
rebates, cost savings and/or discounts. Applying the same principal to daily disposable contact lenses, we could take these factors into
the price equation:
Try new pricing and promotional
strategies: Consider discounting per box
retail price for annual supply purchases. I call
that an In-Office Instant Rebate. The price
yielded on higher sales volume will offset any
margins lost on a per box purchase.
Make it easy for the patient to do
business with you: Offer free direct-ship
for all daily disposable orders. Many patients
will take advantage of the large manufacturer
rebates.
Develop a Goal
Take a snapshot of where your
current daily disposable sales are
as a starting point. Most distributors or manufacturers can provide
your total daily disposable sales as
a percent of overall contact lens
sales. Use those numbers to take a
unified approach to moving your
numbers in a specified direction.
The daily disposable modality is a
great product to consider renewing your practice’s contact lens
focus. CLS
Dr. Miller is in a partnership private practice in
Powell, Ohio, and is an adjunct faculty member
for The Ohio State University College of Optometry. He has received honoraria for writing,
speaking, acting in an advisory capacity, or research from Alcon, Allergan, CooperVision, and
Visioneering Technologies. You can reach him
at [email protected].
CONTACT LENS SPECTRUM/SPECIAL EDITION 2013 •
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The Business of Contact Lenses
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Winning the Race
T
he first person to cross the finish line wins the
race. That’s a truism in running, swimming, cycling and car racing. And, in my experience, it’s a
safe bet that the first eyecare practitioner (ECP)
to cross the finish line wins the
race too. Of course, the race and
finish line for an ECP doesn’t
involve the waving of a checkered
flag. Instead, it means increased
profits and a healthier, more
vibrant practice.
Winning in Practice
But what’s our equivalent of the
race and finish line? It awaits practitioners with the foresight, wisdom and business acumen to
realize the benefits of bringing
“firsts” to their patients; being
known in their communities as the
go-to guy or gal for everything
new in eye care. And the first we’re
talking about here is new contact
lens technology. As in sports, the
first one wins. In this case, the first
ECP to offer the latest technology
to his patients, and those patients
who benefit from the technology,
are the winners.
Why Winning is Important
If you’re the first ECP in your
area to offer a new technology
contact lens, your patients are
more likely to perceive you as
ahead of the curve compared to
others.
It’s just plain common sense
to think that those who offer
new technology first are technologically ahead of those who do
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not. This perception of being an
expert percolates down to all aspects of your practice. “If they offer the latest contact lenses, they
must do everything else really well
too.” You wouldn’t expect a cardiac surgeon who performs the
latest surgical procedure to offer
leeches as an alternative therapy.
An extreme example? Yes, but it
What’s our
equivalent to
the race and the
finish line?
proves the point. Patients in offices offering new technology
don’t expect, and won’t receive,
HEMA lenses. In fact, we often
define and judge our peers based
on their proclivity to embrace and
espouse new technologies. If we
do it, don’t you think our patients
will, too? In other words, impressed patients will spread the
word, and free word-of-mouth
marketing is the best kind.
The other benefit to being the
first to offer new technology is an
economic one. Early adopter patients gravitate to early adopter
ECPs. As such, they aren’t deterred by slightly higher prices.
Offering patients the newest in
CONTACT LENS SPECTRUM/SPECIAL EDITION 2013
contact lens technology might not
get you an Apple iPhone line outside your office, but conceptually,
the idea is the same. Satisfied patients = long-term patients, and
long-term patients generate more
income and loyalty over time.
This is Economics 101 and it’s
been demonstrated hundreds of
times. We’ve heard stories of people who paid hundreds of dollars
for calculators in the seventies, but
what about the stories of those
who SOLD those calculators?
They enjoyed a nice economic
ride because they were among the
first to offer “new technology.”
Check Your Opinion at the Door
A key point to winning and being first is that it is the patient,
not the ECP, who ultimately decides if the race is even worth running. It is the patient who will
determine if the added benefits of
a new contact lens are worth the
entrance fee to participate in the
race. It is NOT and should not be
the ECP’s place to decide this for
the patient. Doing so will cost
your practice thousands of dollars.
Prejudging a patients’ desire to
acquire and pay for new technology can be the costliest practicebuilding mistake you can make.
Your Trophy Awaits
The race is yours to win or
lose. But to do either, you have to
participate. And if you participate
NOW, the odds of winning are
astronomically high! CLS
Dr. Gerber is the president of the Power Practice, a company offering proven and comprehensive practice and profit building systems.
You can reach him at www.PowerPractice.com
and follow him on Twitter @PowerYourDream.
www.clspectrum.com
Pediatric and Teen CL Care
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Why Daily Disposable Lenses
Make Sense for Children
D
aily disposable lenses offer a number of advantages for children, and parents often appreciate
the advantages of convenience and compliance.
They also want the best visual performance for
their children and may worry
about the child’s level of responsibility. Doctors often feel more
comfortable fitting children in
daily disposable lenses, too (Sindt,
Riley 2011). With the simplicity
of the daily disposable replacement system and the benefit of
enhanced compliance (Dumbleton 2009), it’s no surprise that
children are prescribed the highest proportion of daily disposable
contact lenses (Efron 2011).
Optimizing Vision
Most common pediatric prescriptions are available in daily
disposable lenses, and several
studies have found that these
lenses provide better vision compared to reusable daily wear soft
lenses, with fewer symptoms of
cloudy vision (Nason et al 1994,
Solomon et al 1996, Fahmy et al
2010). Furthermore, myopic children under 12 report better
vision-related quality of life when
fit with contact lenses compared
to eyeglasses (Rah et al 2010).
Improving Comfort
Comfort is enhanced by placing a fresh lens on the eye each
day, thereby eliminating biofilms
that may build up in a lens case
www.clspectrum.com
(Chalmers et al 2012). Lens
deposits may lead to symptoms
of dryness and discomfort. Daily
disposable hydrogel lens wearers
have fewer toxic and hypersensitivity reactions (Radford et al
2009) than reusable lenses, and
these lenses have been shown to
improve the signs and symptoms
of tired, irritated eyes, blurred vision, redness, discomfort, deposits
and dryness (Fahmy et al 2010).
Daily disposable lenses are
available in silicone hydrogel, a
material that has been extensively
studied and shown to minimize
hypoxic signs, such as limbal hyperemia, and improve comfort.
Replacing the lens daily reduces the build-up of denatured
proteins and other antigens that
accumulate on the lens during
wear. In one study, some patients
reported they were able to discontinue allergy medications
when using daily disposable contact lenses (Hayes et al 2003).
Better Compliance
Poor patient compliance may
lead to adverse events, and poor
compliance with care regimens is
rampant among contact lens
wearers. But daily disposable
lenses require only proper hand-
washing prior to insertion and
removal. It may be difficult for
parents to monitor their child’s
compliance, so reducing the
number of steps to maintain compliance makes parents and doctors more confident that children
will be able to enjoy contact lens
wear without problems.
Cost Comparison
Children are more likely to engage in part-time contact lens
wear (Efron et al 2011), and daily
disposable lenses are less expensive
when worn 1 to 4 days per week
compared to reusable lenses. They
equal the cost of reusable lenses at
5 days per week of wear and are
slightly more expensive when
worn full time (Efron et al, 2010).
Parents appreciate having replacement lenses on hand in case children damage or tear lenses.
Overall, many parents feel the
benefits of safety and compliance
outweigh any cost concerns.
From comfort and convenience to improved vision, daily
disposable lenses are a great vision correction option for pediatric patients. CLS
For references, please visit
www.clspectrum.com/references.asp
and click on document SE2013.
Dr. Sindt is a clinical associate professor of
ophthalmology and director of the contact lens
service at the University of Iowa Department of
Ophthalmology and Visual Sciences. She is the
past chair of the AOA Cornea and Contact Lens
Council. She is a consultant or advisor to Alcon
Vision Care and Vistakon and has received
research funds from Alcon. You can reach her
at [email protected].
CONTACT LENS SPECTRUM/SPECIAL EDITION 2013 •
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Treatment Plan
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Contact Lens Discomfort: Can
Past Workshops Provide Insight?
C
ontact lens-related discomfort, especially late in
the day or after prolonged near activities, is a
significant problem for many of our patients. My
column usually focuses on the frank treatment of
anterior segment and contact lens
conditions. In this column, I will
summarize what we know about
contact lens-related irritation
based on what we’ve learned from
the DEWS Report and the MGD
Workshop. The DEWS report
cited contact lens discomfort and
dryness as primary reasons why
our patients become less tolerant
of contact lens wear (DEWS
Report). Some of these patients
are known (complainers) and some
unknown (silent tolerators) to our
staff and ourselves. The former are
likely to drop out of contact lens
wear entirely. Between 50 and
75 percent of all patients complain
of some form of ocular irritation
while wearing contact lenses
(DEWS Report). Dropout rates
for contact lens wearers have been
reported to be between 12 and
28 percent, depending on the criteria used in the particular study
(Schlanger, 1993; Weed et al,
1993; Pritchard et al, 1999; Young
et al, 2002; Richdale et al, 2007;
Rumpakis, 2010; Dumbleton et al,
2013). More troubling is that despite advances in lens materials,
wetting agents and designs, not
much has changed over several
decades with regard to contact lens
comfort.
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According to the 2007 DEWS
Report, dry eye as defined by the
report is broadly defined as aqueous (Sjogrens or non-Sjogrens) and
evaporative (MGD). Contact lenses are seen as extrinsic factors that
affect the tear film, causing evaporative effects. This may be the result of a thinning of the pre-lens
tear film or an insufficient wetting
of the contact lens surface, both of
which affect tear film stability on
the anterior surface of the contact
lens. Material properties may lead
to wettability issues with additional
issues caused by lens deposition in
the form of denatured protein and
lipids. This can be addressed using
adequate lens care regimen compliance, but also through the prescribing of daily disposable contact
lenses. Although contact lenses
cause evaporative effects, they may
also disturb aqueous production
through a sensory reflex block
mechanism. Higher water contact
lenses have been associated with
dryness, however this has not been
a universally accepted truth and
thus remains controversial within
the field (DEWS Report).
Additional information about
the effects of contact lens on the
tear film as they relate to the meibomian gland is described in the
CONTACT LENS SPECTRUM/SPECIAL EDITION 2013
MGD workshop report. (Knop
et al, 2011) As reported, because of
its action on the meibomian gland,
estrogen treatment can lead to tear
film instability and reduced contact
lens tolerance (Knop et al, 2011).
Contact lenses may also cause epithelial keratinization as well as
meibomian gland orifice obstruction that can further complicate
successful wear. It has also been
noted that contact lens wearers
have a high meibomian gland drop
out rate that may be related to the
keratinization cycle, however the
precise mechanism is not known.
This dropout rate mimics what is
found in the normal aging process.
A critical reading of two well
regarded published reviews on
ocular dryness and meibomian
gland dysfunction may help in
addressing many issues that affect
contact lens patients. Further
management in the form of topical
drops, contact lens care systems
and novel contact lens technologies may further help more
patients stay comfortable throughout the day, reduce intolerance and
limit drop outs.
For references, please visit
www.clspectrum.com/references.asp
and click on document SE2013.
Dr. Miller is an associate professor and chair of
the Clinical Sciences Department at the University of Houston College of Optometry. He is a
member of the American Academy of Optometry and the AOA. He is a consultant or advisor
to Alcon and Vistakon and has received research funding from Alcon and CooperVision
and lecture or authorship honoraria from Alcon
and Bausch + Lomb. You can reach him at
[email protected].
www.clspectrum.com
Contact Lens Spectrum 13th SE
UNIQUE WATER GRADIENT
33%
>80%
THIS IS WHY lasting lubricity
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>80%
WATER CONTENT (%)
DAILIES TOTAL1® Water Gradient Contact Lenses maintain 100% of their
lubricity after a day of wear.1 And because lubricity is highly predictive of
contact lens comfort, lasting lubricity means lasting comfort.2, 3, 4
>80%
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Contact Lens Cross-Section
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PERCENT OF LUBRICITY FACTOR
The First and Only Water Gradient Contact Lens
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Time of
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UNIQUE WATER GRADIENT
LASTING LUBRICITY
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Features different surface
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Lens maintains 100% of its
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Let your patients experience the DAILIES TOTAL1® contact lens difference today.
100%
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Time of
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PERFORMANCE DRIVEN BY SCIENCE™
1. Alcon data on file, 2011.
2. Brennan N. Contact lens-based correlates of soft lens wearing comfort. Optom Vis Sci. 2009;86:E-abstract 90957.
3. Coles CML, Brennan NA. Coefficient of friction and soft contact lens comfort. American Academy of Optometry. 2012;E-abstract 125603.
4. Kern JR, Rappon JM, Bauman E, Vaughn B. Assessment of the relationship between contact lens coefficient of friction and subject lens comfort. ARVO 2013;E-abstract 494, B0131.
5. Thekveli S, Qiu Y, Kapoor Y, Kumi A, Liang W, Pruitt J. Structure-property relationship of delefilcon A lenses. Cont Lens Anterior Eye. 2012;35(suppl 1):e14.
6. Angelini TE, Nixon RM, Dunn AC, et al. Viscoelasticity and mesh-size at the surface of hydrogels characterized with microrheology. ARVO 2013;E-abstract 500, B0137.
See product instructions for complete wear, care, and safety information. © 2013 Novartis 6/13 DAL13224JAD
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Contact Lens Spectrum
UNIQUE WATER GRADIENT
5/13
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33%
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DAILIES TOTAL1® Water Gradient Contact Lenses feature an
increase from 33% to over 80% water content from core to
surface* for the highest oxygen transmissibility, and lasting
lubricity for exceptional end-of-day comfort.1, 2, 3
The First And Only Water Gradient Contact Lens
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OUT OF 10
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~100%
COMFORT
COMFORT
Enlarged Water Gradient
UNIQUE WATER GRADIENT
LASTING LUBRICITY
OUTSTANDING COMFORT
Features different surface
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optimizing both surface
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Lasting lubricity for
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Let your customers experience the DAILIES TOTAL1®
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100%
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50%
50%
0.0%
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100% 100%
100% 100%
Time of
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Time of
Insertion
Time of
Removal
Removal
Time
of
(average
14 hours)
(average 14 hours)
PERFORMANCE DRIVEN BY SCIENCE
TM
*In vitro measurement of unworn lenses.
1. Based on the ratio of lens oxygen transmissibilities among daily disposable contact lenses. Alcon data on file, 2010.
2. Based on critical coefficient of friction measured by inclined plate method; significance demonstrated at the 0.05 level. Alcon data on file, 2011.
3. In a randomized, subject-masked clinical study, n=40. Alcon data on file, 2011.
4. Angelini TE, Nixon RM, Dunn AC, et al. Viscoelasticity and mesh-size at the surface of hydrogels characterized with microrheology. ARVO 2013;E-abstract 500, B0137.
See product instructions for complete wear, care and safety information. © 2013 Novartis 04/13 DAL13097JAD
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