Download A Contact Lens that Works with the Tear Film

A Contact Lens that Works with the Tear Film
In DAILIES® AquaComfort Plus® contact lenses,
multiple wetting technologies work in tandem to maintain
tear film integrity—and all-day comfort. — Kristopher A. May, OD, FAAO
rather than chemical processing, to polymerize the lens
Research over the last decade has expanded the
material. This efficient photo-lithographic process does not
traditional three-layer (mucin/aqueous/lipid) model of the
require the chemical byproduct-extraction step necessary
tear film to a more complex continuum. We now see that
for other contact lens manufacturing processes.4
mucins are both bound to the epithelial glycocalyx and
The material, nelfilcon A plus, contains polyvinyl
dissolved in the aqueous tears; that proteins, electrolytes,
alcohol (PVA), a water-soluble
growth factors, and antioxidants
polymer commonly used as a
comingle in aqueous solution;
PROVEN PERFORMANCE, BUILT-IN
wetting agent in artificial tears.
and that a thin complex of
Wolffsohn and coworkers examined the
Most of the PVA in DAILIES®
phospholipids, fatty acids, and
clinical performance of four daily disposable
1
AquaComfort Plus® contact lenses
lens types, all of which had some form
esters prevents evaporation.
of comfort enhancement. Lenses were
is bound to the lens matrix, but
When functioning properly,
worn for 8, 12, and 16 hours; and clinical
the small amount of unbound PVA
the tear film reduces friction
measurements (taken with the lens in place)
present in the lenses is gradually
during blink, protects against
included pre-lens non-invasive TFBUT, tear
squeezed from the lens matrix by
infection, delivers nutrients and
prism height, bulbar hyperemia, and ocular
normal blinking.5
clears wastes; and, importantly,
surface temperature.5
The moisturizing agent
provides a smooth refracting
For all tested lenses, the tear prism
polyethylene glycol, a mediumsurface for light entering the eye.
height, pre-lens non-invasive TFBUT, and
sized molecule that binds to PVA
Disruption of the tear film can
ocular surface temperature decreased after
and further extends its release, is
set the stage for the signs and
longer hours of wear. However, the tear
also embedded in the lens matrix.
symptoms of dryness to develop.1
film was found to be most stable on the
®
®
It takes 2 to 4 hours to dissipate
surface of DAILIES AquaComfort Plus
and so helps to support a stable
Add a Contact Lens
contact lenses, whose multi-tier wettability
pre-lens tear film early in the day.
technology outperformed its rivals.5
When placed on the eye, a
Hydroxypropyl methylcellulose
contact lens splits the tears into
(HPMC), a smaller molecule added to the packaging solution
a pre-lens tear film and a post-lens tear film. Dividing the
of DAILIES® AquaComfort Plus® contact lenses, enhances
tears in this way causes the layer on top of the lens to be
comfort on insertion and through the initial 20 to 30 minutes
thinner and break up more rapidly. This loss of volume
of wear. This staged combination of wetting strategies results
and faster breakup, which happen irrespective of lens
in a stable tear film—and all-day comfort for wearers.6
type, is believed to be due to thinning of the lipid layer.2
Because they do not require care solutions or complex
A shortened tear film breakup time (TFBUT) can leave
cleaning regimens, I like to think of daily disposable
parts of the lens’ front surface exposed to air, and these
lenses as having “built-in” patient compliance. Prescribing
dry spots can affect lens performance. Soft contact lenses
DAILIES® AquaComfort Plus® contact lenses—daily
are dynamic structures: When covered by tear fluid, the
disposables with “built-in” comfort and tear film stability—
hydrophilic heads of the lens polymer chains are stable at
helps keep my contact lens patients happy and healthy.
the lens surface; but when the tears break up and expose
areas of the lens surface to air (which is hydrophobic), the
hydrophilic moieties within the lens are driven toward the
Kristopher A. May, OD, FAAO, practices at Coldwater
Vision Center in Coldwater and Ashland, MS.
moisture within the lens bulk, leaving hydrophobic (nonwettable) areas on the lens surface.3
REFERENCES
Decreased lens surface wetting leads to greater friction
1. Craig JP, Tomlinson A, McCann L. Tear Film. In: Dartt D, Bex P,
D’Amore P, et al. Ocular Periphery and Disorders. 1st ed. New York:
and greater susceptibility to protein and lipid deposition—
Elsevier; 2010:254-62.
2. Stapleton F, Stretton S, Papas E, et al. Silicone hydrogel contact lenses and the
which can contribute to discomfort for wearers.
ocular surface. Ocul Surf. 2006;4(1):24-43.
Engineered for Tear Film Stability
DAILIES® AquaComfort Plus® contact lenses take a
multi-tiered approach to wettability. First, these lenses
benefit from an innovative manufacturing process called
Lightstream™ Technology, which uses ultraviolet light,
Sponsored by Alcon
3. Nichols JJ, Sinnott LT. Tear film, contact lens, and patient-related factors associated
with contact lens-related dry eye. Invest Ophthalmol Vis Sci. 2006;47(4):1319-28.
4. Nicholson PC, Vogt J. Soft contact lens polymers: an evolution. Biomaterials.
2001;22:3273-83.
5. Wolffsohn JS, Hunt OA, Chowdhury A. Objective clinical performance of ‘comfortenhanced’ daily disposable soft contact lenses. Contact Lens Anterior Eye.
2010;33:88-92.
6. Peterson RC, Wolffsohn JS, Nick J, Winterton L, et al. Clinical performance of daily
disposable soft contact lenses using sustained release technology. Contact Lens
Anterior Eye. 2006;29:127-34.
Rx only
See product instructions for complete wear and care and safety information.
©2013 Novartis 5/13 DAL13256AD