contact lens care and compliance
Comfort Still the Key to Keeping Patients in Lenses for Life
By Susan J. Gromacki, OD, MS, FAAO
Comfortable, healthy, all-day, long-term contact lens wear is our goal for patients and their desire for themselves. However, there are many barriers to achieving this goal. First is the contribution of the environment. As the population of the United States shifts south and west, more and more of our patients are living in arid environments that aren't conducive to keeping contact lenses lubricated. Many of our patients who live in these regions, and even patients who live in other areas of the country, spend a great deal of time in air-conditioned buildings, further drying out their contact lenses.
In addition, there are common systemic medications that cause dryness. As we're well aware, tear production decreases with age, but our patients wish to remain in contact lenses—particularly Generation X, many of whom have worn soft materials their entire lens-wearing lives. And what's more, lens deposition can impede the smooth flow of the tear film, leading to break-up. The end result is that patients reduce their wearing time or discontinue contact lens wear altogether.
Finally, the ingredient that makes our latest generations of soft contact lenses so permeable to oxygen—silicone—is inherently unwettable. Most of the existing silicone hydrogel materials need to include an internal agent or surface treatment to improve hydrophilicity.
Lens manufacturers have tried to augment wettability by incorporating agents into the blister pack or the lens. But some of our patients still need more. Wouldn't it be great if the care system truly contributed to contact lens wettability and comfort?
Early generations of lubricating agents were invented before the advent of silicone hydrogel lenses. The most recent multi-purpose contact lens solutions have been formulated specifically for use with silicone hydrogel lenses.
Of these, Opti-Free PureMoist (Alcon) is the newest. Its novel wetting agent, poly (oxyethylene)-poly (oxybutylene) (EOBO or HydraGlyde Moisture Matrix) was designed to work optimally with the new materials, while still maintaining the ability to work with traditional ones.
The science behind the formulation is fascinating. Poly (oxyethylene) is hydrophilic; it attracts moisture and carries water to the hydrophobic lens sites not wetted by the tear film. The poly(oxybutylene) chains target silicone, surrounding its hydrophobic groups and rendering the surface wettable.
It is evident that multipurpose solutions will play an extremely important role in our lens wearers' comfort going forward. This is great news for practitioners and patients alike. CLS
Dr. Gromacki is a Diplomate in the Cornea, Contact Lenses, and Refractive Technologies section of the American Academy of Optometry. She is Chief Research Optometrist at Keller Community Hospital in West Point, New York.