contact lens management
A Solution for Silicone Hydrogel
New solution addresses the material's special
needs.
BOBBY
CHRISTENSEN, O.D.,F.A.A.O.
The
contact lens solutions available for the last 15 years have fulfilled most of the
needs of our hydrogel contact lens wearers. Then along came the high-Dk silicone
hydrogel lenses. Some patients complained of discomfort and dryness compared with
the older lenses. In addition, practitioners began to document corneal staining
with some of the biguanide-based solutions. It became obvious that silicone lenses
require special care.
In
an attempt to answer this need, Alcon has released Optifree Replenish solution.
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Replenish
provides comfort and disinfection.
Optifree
RepleniSH
PRESERVATIVES
AND ANTIMICROBIALS: Polyquad (polyquaternium-1) and Aldox (myristamidopropyl dimethylamine) 0.0005%.
RECONDITIONING SYSTEM:
Tearglyde; Tetronic 1304 and C9-ED3A (nonanoyl ethylenediaminetriacetic acid)
CLEANING AND BUFFERING AGENT: Sodium citrate
DEMULCENT AND OSMOLARITY AGENT: Propylene glycol
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What to look for
Following are my three main concerns when picking
a contact lens care system for my patients.
►Safety. Disinfection and microbial kill rates are important. The FDA disinfection
guidelines for a "no-rub" solution require a 3.0 log kill of the bacteria Staphylococcus aureus, Pseudomonas aeruginosa and Serratia marcescens. It also requires a 1.0
log kill of yeast Candida albicans and fungi Fusarium solani. In four double-masked,
controlled trials involving 43 investigators over a period ranging from one to three
months, this solution met or exceeded the FDA criteria for microbial disinfection
for bacteria and fungi.
Additionally, some biguanide-based
formulations may cause corneal staining with some silicone hydrogel lenses. Although
corneal staining is not a sight-threatening event, it probably does affect long-term
wearing comfort. My goal is to have the cornea free of staining during contact lens
wear.
►Comfort and wearing time. Comfortable lens wear for 12 to 16 hours per day is my
goal for most patients. In clinical trials, researchers immersed lenses in lysozyme,
the predominate protein in the tears, for seven days. They then soaked groups of
silicone hydrogel lenses (no rubbing) in Replenish overnight and measured the remaining
protein on the lenses. The cleaning efficacy of this solution was 64.3%. This increased
protein removal translates into greater comfort and longer wearing times for patients.
►Improved wetting. Keeping the lens moist late in the wearing period reduces complaints
of drying. The wetting angle of a drop of water on the surface of a lens conditioned
overnight with Replenish was measured at less than 10° after 14 hours of wear.
A low wetting angle means the lens is better able to retain moisture.
The solution matters
Having participated in many contact lens solution
studies over the past 25 years, I can say the clinical data proves that choosing
the correct contact lens care system for each patient will improve successful lens
wear rates. You and your contact lens technician should recommend the care system
you want your patient to use. This is especially true with silicone hydrogel lenses.
DR. CHRISTENSEN HAS A PARTNERSHIP
PRACTICE IN MIDWEST CITY, OKLA. HE'S A DIPLOMATE
IN THE CORNEA AND CONTACT LENS SECTION OF THE AMERICAN
ACADEMY OF OPTOMETRY.
Optometric Management, Issue: April 2006