contact lens case reports
Silicone Hydrogels as Problem-Solving Contact Lenses
BY PATRICK J. CAROLINE, FCLSA, FAAO, & MARK P. ANDRÉ, FCLSA, FAAO

Advances in silicone hydrogel lens technology have rekindled practitioner and patient interest in continuous wear. However, often overlooked is the potential of these materials as a problem-solving modality in daily wear.

High Dk to the Rescue

A case in point is patient JV who presented to our clinic for routine contact lens follow-up with symptoms of mild dryness. The patient had been wearing 58 percent water lenses for three years on a two-week planned frequent replacement schedule. Her lens care consisted of a multi-purpose disinfection system which she used nightly. Slit lamp examination revealed significant limbal hyperemia and subsequent neovascularization OU.

In her book Silicone Hydrogels, Deborah Sweeney, BOptom, PhD, described limbal hyperemia as an engorgement of the limbal capillaries resulting in a circumlimbal flush. This finding is commonly report by our patients as chronic red eyes. In 1997, Eric Papas, PhD MCOptom DCLP, and co-workers clearly demonstrated a relationship between induced limbal hyperemia and lens oxygen transmissibility. In their study, daily and overnight wear of high Dk silicone hydrogel lenses produced no abnormal changes in limbal hyperemia, whereas low Dk lenses showed marked increase in redness in as little as four hours.

Figure 1a. Right eye, conventional hydrogel lens for daily wear. Figure1b. 30 days post Night & Day for daily wear.	Figure 2a. Left eye, conventional hydrogel lens for daily wear. Figure 2b. 30 days post Night & Day for daily wear.

We immediately refit the patient with CIBA Vision Night & Day lenses (Dk 175) to be worn on a daily wear basis. We gave the patient the hydrogen peroxide-based Clear Care system (CIBA Vision) for nightly lens disinfection.

Upon her return one month later, there was a dramatic improvement in her peripheral neovascularization and dry eye symptoms OU (Figures 1a and 1b and 2a and 2b). The combination of the high Dk silicone hydrogel lenses (on a daily wear basis) and the hydrogen peroxide care regimen had a positive effect on the health of the patient's corneas. Whether these change are related to the lenses increased oxygen transmission ,improved peripheral lens design, improved surface properties secondary to the advanced surface treatment or multifactoral remains somewhat unclear.

Conscientious practitioners will want to keep in mind the effectiveness of silicone hydrogel contact lenses as a daily wear modality.

Patrick Caroline is an associate professor of optometry at Pacific University and an assistant professor of ophthalmology at the Oregon Health Sciences University. Mark André is director of contact lens services at the Oregon Health Sciences University.