Download Improving the Experience of Contact Lens Wear

Volume 1, Issue 1
2012
A Learning Resource for Optometrists from the School of Optometry & Vision Science, University of Waterloo, and the School of Optometry, University of Montreal
Improving the Experience of Contact Lens Wear:
Avenues for Reflection and Change
B Y L ANGIS M ICHAUD , OD, MS C , FAAO (D IPL .)
Contact lenses are used as a method of correcting refractive errors. However, their use can be
associated with periods of discomfort as well as occasional pathophysiological reactions. This
inaugural edition of Optometry Rounds presents the latest findings to allow Optometrists to
improve the experience of their patients who wear contact lenses, as well as to share knowledge with
respect to contact lens maintenance. The following specific points will be addressed:
• Physiological effects of contact lens wear
• Clinical significance of deposits and pathogens on the surface of contact lenses
• How to interpret corneal staining related to contact lens maintenance solutions
• Effects of method of wear on patient comfort
Marlee M. Spafford, OD, PhD, FAAO
Professor and Interim Director
Thomas F. Freddo, OD, PhD, FAAO
Professor and Co-Editor, Optometry Rounds
Contributing Faculty Authors:
Sarah MacIver, OD, FAAO
Clinical Lecturer
C. Lisa Prokopich, OD, MSc
Clinical Lecturer
Michelle Steenbakkers-Woolley, OD, FAAO
Clinical Lecturer
Effects of Contact Lenses
Wearing a contact lens induces multiple effects on the eye. Their mere presence, directly upon
insertion, produces an imbalance of the tear film. The thickness of the tear film, found at the surface of
the lens, decreases quickly within the first 30 minutes of wear.1 In addition to the lens, the maintenance
solution could contribute to a reduction in thickness of the tear film.2
Any disruption of the tear film leads to instability and, consequently, to a period of reduced breakup time. Tear film that is unstable results in altered image perception and contributes to the sensation
of ocular dryness.3 Wearing flexible lenses (made from hydrogel and silico-hydrogel) is associated with
a reduction in tear volume and an increase in tear osmolarity.4
The thinning of the tear film, its quicker evaporation at the surface of the lens, and the increase in
tear osmolarity cause rapid accumulation of deposits at the lens surface. These include deposits from
tears and from the immediate environment of the wearer.5 The nature and the quantity of the accumulated deposits are directly related to the material and upkeep of the lens. 6 This accumulation of
deposits led researchers to recommend, as early as the 1980s, the use of disposable lenses.7
In fact, it was discovered that the integrity of the ocular surface is affected by several characteristics
of the contact lens, including the water content, the ionicity, the permeability to oxygen, the modulus
of elasticity of the material, the nature of the surface deposits, and the wettability of the lens once
soiled.
More frequent replacement of the lens reduces, in part, the impact of lens wear on ocular health.
More generally, the selection of maintenance products also has an important impact on the clinical
picture. This choice is made depending on the cleaning and disinfecting action, on the cytotoxicity of
the product and on its biocompatibility, elements that are just as important as the selection of the lens
material itself.8
The method of lens wear and patient characteristics must also be taken into account. The risk factors
are well documented (Table 1). The cumulative presence of these risk factors should encourage the eye care
professional to recommend a safe product linked to a high compliance rate, namely daily disposable lenses.
École d’Optométrie
School Administration:
Christian Casanova, PhD
Director and Professor
Neurophysiology and Imaging
Danielle de Guise, OD, MSc
Associate Director of Cycle 1 Studies
Binocular Vision and Orthoptics
Jocelyn Faubert, PhD, FAAO
Associate Director of Research and Advanced Studies
Professor, Psychophysiology and Visual Perception
Jacques Gresset, OD, PhD, FAAO
Secretary and Professor
Epidemiology and Low Vision
Editorial Committee:
Jean-François Bouchard, BPharm, PhD
Associate Professor, Neuropharmacology
Pierre Forcier, OD, MSc
Associate Professor, Ocular Health
Langis Michaud, OD, MSc, FAAO (Dipl.)
Associate Professor, Contact Lenses
Co-Editor, Optometry Rounds
Judith Renaud, OD, MSc
Assistant Professor, Low Vision
CLINICAL CONSEQUENCES:
• Any contact lens that is placed on the eye can disrupt the ocular balance and the tear film
• Modification of tear film leads to symptoms of discomfort and of ocular dryness
• The more frequent replacement of the lens, in addition to its proper maintenance, will
minimize potential complications
• The response to lens wear is personal and the professional must analyze the risk factors based
on the personal characteristics of the wearer.
Available online at www.optometryrounds.ca
University of Waterloo
School of Optometry & Vision Science
200 University Avenue West, Waterloo, ON N2L 3G1
Université de Montréal
École d’Optométrie
3744 Jean-Brillant, Montreal, QC H3T 1P1
The editorial content of Optometry Rounds is determined
solely by the School of Optometry & Vision Science,
University of Waterloo, and the School of Optometry,
University of Montreal.
Table 1: Risk factors associated with the development of
inflammatory episodes related to contact lens wear
Table 2: Treatment of giant papillary conjunctivitis
• Type and material of contact lenses worn (avoid
conventional lenses or first-generation disposable lenses)
1) Do not wear lenses for
2 weeks
– Prescribe daily disposable
lenses if the patient cannot
or will not wear eyeglasses
1) Consider more
frequent use of
disposable (ideally
daily disposable)
lenses
2) Prescribe topical steroids
– loteprednol 0,5 % QID x
2 weeks, then BID once
the lenses are re-introduced
(x 2-4 weeks)
2) Educate the patient
on the importance of
compliance and
hygienic factors
surrounding the use
of contact lenses
• Adaptability (avoid tight lenses or those with restricted
movement)
• Lens power (>5.00 D of myopia)
• Duration of wear (avoid prolonged wear)
• Frequency of contact lens replacement (daily disposable
lenses are preferable)
• Maintenance system used (hydrogen peroxide versus
all-in-one solutions)
• Hygienic methods (compliance)
• Age (< 25 years)
• Smoking
• Sex (men are at greater risk, particularly younger men)
Initial therapy
3) Once the inflammation and
the reaction have cleared up,
consider the use of combined
therapy with anti-allergy
medications (olopatadine BID
x 4-6 weeks)
Long-term support
QID = 4 times daily; BID = twice daily
Deposits and pathogens on
the surface of contact lenses
The contact lens accumulates deposits as early as
within the first minutes of wearing them. 9 These deposits
form a layer or a film that is comprised of tear film elements 10 (proteins, carbohydrates, mucus, fat) 6 as well as
bacteria and polysaccharides that colonize.11 Bacterial toxins can also be trapped, and later released within the ocular
environment.
Mechanical effect
Deposits have a primary mechanical impact, leading to
complications. They contribute notably to immune reactions.
Mechanical impact results in tissue irritation and the presence of papillary reactions. Giant papillary conjunctivitis
(Figure 1), first identified following hydrogel lens wear, can
also occur with lenses that are disposable,13 gas permeable,14
scleral, 15 and hybrid. 16 Secondary reaction to the deposits
would be considerably less important with the use of silicohydrogel lenses.17 The presence of these papillae is associated
with symptoms of dry eye, but does not influence the tear
film break-up time.18 Treatment for this condition is summarized in Table 2.19
Figure 1: Giant papillary conjunctivitis
Adapted from: Friedlaender MH, Howes J. Am J Ophthalmol. 1997;123(4):455-464.
Immune effects
Deposits alter the composition and the immune action of
the tear film.20 This change can lead to a higher susceptibility
of the eye to infections and also result in more significant
deposits of material at the surface of the lens, thus increasing
patient discomfort.17 Contact lenses also initiate immune system reactions (Table 3). The risk factors for developing such
reactions have been previously identified (Table 1). The
occurrence of inflammatory episodes, such as contact lens
acute red eye (CLARE),21 may be related to an isolated factor
or to a combination of factors.22 Thus, daily disposable lens
factors associated with highest risk include individuals aged
≤25 years, males, contact lens wear longer than 6 months, and
a correction of >5.00 D of myopia.
Extended wear is particularly notable. In these cases,
beyond the aforementioned risk factors, the presence of
biofilm on the lens surface is a primary factor of the immune
reaction.23 With daily disposable as with extended use, this
would be directly related to the development of sterile corneal
infiltrates while wearing silico-hydrogel lenses.24
The pathogens are mainly gram-negative bacteria of the
Pseudomonas family, although other new microbes (Achromobacter, Stenotrophomonas, and Delftia) have recently been
identified.25 The environment of the wearer (contaminants,
moist environment, agricultural setting, etc), the individual
characteristics of the ocular health, and a lens with limited
flexibility on the eye are likely to increase the risks of infiltrating keratitis (Figure 2).26 However, the development of these
Table 3: Inflammatory episodes associated with contact
lens wear
•
•
•
•
•
•
Photo: Dr. Langis Michaud – Université de Montréal
Acute episodes of red eye
Corneal erosion
Conjunctivitis (allergic, viral, bacterial)
Infiltrating keratitis
Microbial keratitis
Anterior and/or posterior blepharitis
Figure 2: Sterile inflammatory reactions in a lens wearer
Photo: Dr. Langis Michaud – Université de Montréal
infiltrates would not be linked to the presence of corneal
staining, in contrast to what was suggested in a study conducted by Papas et al.27
A less significant accumulation of deposits reduces the
symptoms of the wearer28 and minimizes the impact of contact lens wearing on eye health. This is an argument supporting the more frequent disposal of lenses. The daily disposable
lens, therefore, has a clinical advantage over the other types.
CLINICAL IMPLICATIONS:
• All contact lenses accumulate deposits beginning
within the first minutes of wear.
• Adsorption of deposits on the surface of the lens
induces a mechanical effect and causes inflammatory
reactions at the ocular surface.
• Prolonged wear is associated with additional risk factors.
• Presence of pathogens at the surface of the lens and in
the storage case is the main factor for the development
of corneal inflammatory reactions.
• Corneal staining is not associated with a greater risk of
corneal infection.
• Frequent lens disposal minimizes the risk of complications.
Interpretation of Corneal Staining
Fluorescein staining of the cornea occurs in various cases:
dry eye29, physical trauma to the cornea, and following contact
lens wear.30 In the latter case, the lens type, its adaptation,31 as
well as the lack of corneal oxygenation have been associated
with the presence of dotted staining, which occasionally coalesce to form plaques. Contact with certain materials in solutions 32 has also been identified as the probable cause of a
different type of corneal staining: dotted, diffusely over the
entire corneal surface, or affecting only the corneal limbus
region, appearing at the beginning of wear, with no long-term
clinical consequences. Because of these differences from classical metabolic staining, the relationship between materials and
solutions has been the subject of much debate, and a consensus
on the real cause of its occurence has been difficult to reach.
The term “solution induced corneal staining” (SICS)
refers to a punctate staining, of a minimal grade 1 intensity,
affecting at least 4 out of the 5 areas of the cornea (superior,
inferior, nasal, temporal, and central; Figure 3).33 Its presence
is mainly associated with contact lens solutions and must be
differentiated from other forms of staining that could affect
the cornea. Unlike other types of staining that are associated
with eye disease, a lack of oxygenation or surface erosions,
SICS is transient in nature, 34 disappearing within a few
hours. The peak in observation usually occurs in the first
2 hours of lens wear, varying according to the composition
of the solution. Certain agents, such as polyquaternium-1
(PQ-1), are quickly released into the ocular environment,
causing a very brief staining, while polyhexamethylene
biguanide (PHMB)-based solutions have a more noticeable
and lengthy action.35 Irrespective of the agent in question,
the cornea normally reveals no further symptoms 6 hours
following exposure.36
The clinical significance of this transient staining remains
a focus of research. Initially, such staining was believed to be
associated with a tear in the cellular surface, threatening the
epithelial barrier of the cornea, 37 or even predisposing the
wearer to inflammatory reactions of the cornea. 38 Other
hypotheses have been proposed, including that of a particular
attraction between mucin and PHMB, a special relationship
that would occur to a lesser extent with PQ-1.39 The hyperfluorescence theory explains the transitory nature of SICS,
though it does not completely explain its presence. In fact, in
the absence of staining dye, changes can be seen on the epithelial surface, which casts doubt on fluorescein-mucin attraction. None of these hypotheses can explain both the clinical
features and the symptoms (or absence of symptoms) experienced by the wearer. In fact, contact lens wearers presenting
with SICS report more severe discomfort and reduced vision
compared to those who do not experience SICS.40
The most plausible hypothesis comes from the analysis of
shed epithelial cells following staining. This analysis reveals
that fluorescein accumulates to a greater extent in the cell
rather than in the interstices, and therefore does not result in
breakage or loss of tight junctions of the corneal surface. The
transient staining would more likely be a sign of cell apoptosis, as an indication of imminent premature death.41 In this
sense, the visible staining resulting from the solution-lens
association could be interpreted as a sign of a physical-chemical challenge suffered by the cell during contact lens wear,
beyond its tolerance threshold. The latter is, in part, a factor
Figure 3: Solution induced corneal staining (SICS)
Photo: Dr. Langis Michaud – Université de Montréal
pointing to the variations of symptoms and clinical signs
among individual wearers.
Studies have shown that limiting the exposure to solutions or, failing that, scrubbing and rinsing the lens prior
to insertion, would contribute to the reduced incidence of
SICS.42 Similarly, the use of hydrogen peroxide can largely
eliminate the impact of cleaning solutions on the cornea.
In addition, hydrogen peroxide solutions are associated
with fewer risk factors that could trigger corneal infiltrations compared to PQ-1 or of PHMB-based43 solutions. In
the latter cases, as previously mentioned, the presence of a
bacterial biofilm that is not eliminated by solutions, when
in conjunction with wearing rigid contact lenses, predisposes the wearer to infiltrates.
According to Bendamwar, 44 the interpretation of
staining should therefore be revised: moderate fluorescence is a sign of healthy cells, hyperfluorescence (only
visible with a biomicroscope) is a sign of apoptosis, and
the black regions, lacking fluorescence, identify zones of
dead cells.
CLINICAL IMPLICATIONS
• Corneal staining caused by maintenance solutions should not be interpreted as being related to
pathological causes: dry eye, trauma causing an
epithelial tear and hypoxia.
• Corneal staining due to solutions translates into a
physiological stress involving the epithelial cells:
it includes an apoptotic (premature death) cellular state.
• Certain lens-solution interactions contribute to
the generation of more pronounced corneal reactions. Hydrogen peroxide appears to be the least
compromising solution for ocular health.
• The absence of any solutions – ie, daily disposable
lenses – is the best alternative for eliminating
SICS.
Effects of the Method of Wear
on Patient Comfort
The change from conventional to disposable lenses
has allowed prescribers to improve overall clinical ocular
features. In fact, this has contributed to increased wearer
satisfaction in terms of improved visual acuity, decreased
corneal staining, lower intensity injections at the limbus,
fewer deposits on the lens, and episodes of infection.
Monthly disposable lenses are superior to those that are
disposable every 3 months for all of these factors,45 which
explains why these lenses dominate the Canadian market.
However, although the conditions of wear have
improved in users of disposable lenses, at least half of
wearers continue to report multiple adverse effects (Table
4). These symptoms vary from patient to patient, and
they change depending on the wearer’s environment, on
the products used, on the conditions of wear, and on
patient compliance. The discomfort felt with contact
lenses increases with time: beginning from the third week,
monthly lenses become less and less comfortable. Simi-
Table 4: Adverse effects commonly reported by
wearers of disposable contact lenses
• Fluctuating vision
• Eye strain
• Dryness
• Redness
• Deposits
• Irritation
• Discomfort
• Sensation of the lenses on the eye
larly, the second week of wear of bimonthly disposable
lenses is typically marked by reduced wearer comfort.
How, then, can we further improve the clinical features of the wearer? One of the first ways is to consider
the noncompliant behaviour of prescribers: nearly 20%
of eye care professionals recommend monthly disposal of
lenses that are, in theory, made to be disposed of every 2
weeks.46 Patient compliance with respect to maintenance
instructions and the prescribed method of wear ranks
second among these issues. In fact, fewer than 10% of
patients adhere to the instructions given by the professional and the manufacturers.47 The patient should be
educated and informed of the potential risks of improper
lens wear, notably the increased risks of ocular infections48 or other clinical signs and symptoms, as well as
reduced tolerance to contact lens wear.49 It is essential to
discuss these issues at each appointment. Patients should
be made aware of their bad wear habits, as most believe
that they are compliant with information regarding
proper lens wear.50
Prescribing a pair of glasses to a contact lens wearer
increases their adherence because it gives them an alternative for vision correction, avoiding the abuse of contact
lens wear. 51 The transition to hydrogen peroxide as a
maintenance system has long been perceived as a means
of improving symptoms and comfort of the wearer. This
alternative has proven to be more effective than all-in-one
solutions.52 However, a new generation of maintenance
solutions has recently been introduced that may challenge
the superiority of hydrogen peroxide. One solution in
particular may allow for the preservation of the immune
functions of the tear film, which could increase the ocular
protection of the wearer.53 Another may be associated
with a greater disinfectant capacity compared to that of
peroxide,54 all the while eliminating irritants. However,
patient compliance is essential: not rubbing the lens, leaving the bottle open, and not completely emptying the case
after each use are all factors that reduce the disinfectant
properties, increasing the risk of infection and contributing to deposits that are left on the lens surface. 55 The
patient’s comfort is thereby directly affected.
The optimal approach to improve contact lens wear
is to use daily disposable contact lenses. In fact, a lens
that is replaced every day does not accumulate significant
deposits on its surface, as the wearer is not chronically
exposed to cleaning chemicals. Finally, patient compli-
ance improves, approaching nearly 90%.56 The introduction of daily disposable lenses, made from a material that
is highly permeable to oxygen, ensures the necessary oxygenation of the cornea. Those that are less permeable
nevertheless still provide a permeability that approaches
the minimum thresholds established by the Morgan criteria (Dk/t [permeability divided by thickness] of 24 in
the centre and 35 on the periphery).57 This reduced permeability must be compensated for by the appropriate
movement of the lens, in order to allow for optimal tear
exchange. Debris is then removed and oxygen supply by
the tear film can occur. A lens that can move also reduces
the risk of inflammatory episodes.27
A prescription for daily replaceable lenses must therefore no longer only be considered for part-time usage,
but must become a common practice in order to maintain ocular health in short-, medium-, and long-term
users.
These lenses can be adapted for both young patients,
from the age of 8 years, and older patients.58 Additional
features are becoming increasingly available, with efficient designs for the correction of common refractive
errors as well as for the correction of astigmatism or
presbyopia.
Daily replacement lenses have historically been
ignored mainly because they were considered too costly
for the patient; however, recent data indicate that the cost
to the patient of lenses worn 5 days/week is similar to that
of lenses that are replaced every 2 weeks or every month.
At a lower frequency (worn <5 days per week), daily disposable lenses offer a significant economic advantage.59
Other Advantages of Daily Disposable Lenses
Daily disposable lenses are associated with a reduced
risk of developing eye complications, including microbial keratitis. That is largely due to the fact that the lens
does not become contaminated through contact with
pathogens that have colonized in the storage case.60 Studies show that up to 80% of cases are contaminated with
bacteria and nearly 50% by fungi. Contamination
increases with time: older cases are at greater risk than
newer ones. This contamination by pathogenic agents
represents a major risk of eye infections. To reduce the
risk, it is recommended to avoid lens contact with the
water in the case, to store the case somewhere other than
in the bathroom (the bedroom is the ideal location), and
to change the case every month.61 Here again, the use of
daily disposable lenses helps avoid this problem.
Daily disposable lenses are also protective against the
effects of allergens in the eye 62 and against the sun’s
harmful rays (ultraviolet protection), in some cases63.
According to a recent study, the clinical signs related to
eye health (staining, hyperemia, papillary reaction) in
addition to various symptoms (Table 4) were improved
by wearing daily disposable lenses versus longer-wear
lenses,28 even if daily disposable lenses were less permeable to oxygen than the monthly disposable ones.
CLINICAL IMPLICATIONS
• Frequent replacement of lenses offers clinical
advantages (disposable versus conventional)
• Daily disposable lenses are the optimal solution
to lens wear problems. These lenses improve
patient comfort versus less frequently replaced
lenses and reduce the risk of complications (clinical signs of infection, inflammation, and risk of
microbial keratitis).
• Daily disposable lenses eliminate reaction to
cleaning solutions as well as secondary contamination in the transmission of pathogens that have
colonized in the lens case.
Conclusion
Contact lens wear can be enjoyable and easy for many
patients. However, a vast majority continue to wear their
lenses despite signs and symptoms that are incompatible
with long-term maintenance of optimal eye health.
There are several strategies to improve the experience of contact lens wear:
• Establish the needs and individual characteristics of
the wearer
• Tailor the lenses according to these patient characteristics, avoiding potential risk factors
• Implement optimal strategies: minimize risk factors
and recommend the use of maintenance products that
cause the fewest possible adverse clinical consequences
• Recommend switching to daily disposable lenses,
which is the most effective means to counter wearer
symptoms and potential complications
• Educate and advise users and conduct regular followups in order to increase compliance
• Comply with the norms and standards of practice in
order to reduce noncompliance on the part of prescribers and of eye care practitioners
For many professionals, the above may represent a
paradigm shift with respect to regular practice. Failure to
adopt this approach reduces the number of patients who
will become contact lens users, thereby limiting the economic potential of the practice, and potentially depriving patients of a method of vision correction that can be
both pleasant and practical.
Dr. Michaud is an Associate Professor and the Chief of the
Contact Lens Department, Clinical Research, School of
Optometry, University of Montreal, Diplomate of the
American Academy of Optometry as well as of the Scleral
Contact Lens Organization (US).
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Dr. Michaud received speaker fees from Bausch & Lomb, Allergan,
Genzyme Canada, CooperVision, Alcon, Ciba Vision, and PRN
Canada, and research funding (Université de Montréal) from Laboratoires Blanchard, Johnson & Johnson, Genzyme Canada, Abbott
Medical Optics, Alcon, Ciba Vision, and the Canadian Association
of Optometrists.
A Partnership for Excellence in Continuing Optometry Education
Optometry Rounds is made possible through independent sponsorships from
Alcon Canada and Novartis Pharmaceuticals Canada Inc.
© 2012 School of Optometry & Vision Science, University of Waterloo, and School of Optometry, University of Montreal, which are solely responsible for the contents. The opinions expressed
in this publication do not necessarily reflect those of the publisher or sponsor, but rather are those of the authoring institution based on the available scientific literature. Publisher: SNELL
Medical Communication Inc. in cooperation with the School of Optometry & Vision Science, University of Waterloo, and School of Optometry, University of Montreal. All rights reserved.
The administration of any therapies discussed or referred to in Optometry Rounds should always be consistent with the approved prescribing information Canada.
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