contact lens materials
Choosing Lens Materials to Solve Dryness Complaints
BY JEFF SCHAFER, OD, MS

Dryness has historically complicated contact lens wear to the extent that it often causes patients to stop wearing lenses. It's been reported that up to 75 percent of contact lens wearers experience at least occasional ocular dryness.

How we manage contact lens dryness has changed dramatically over the last five years. New contact lenses have entered the market and have given us a variety of options to help improve the comfort of our patients.

Silicone Hydrogels

When silicone hydrogel materials first entered the market, anecdotal evidence of improved dryness symptoms began surfacing in patients refit into balafilcon A (PureVision, Bausch & Lomb) and lotrafilcon A (Night & Day, CIBA Vision). Many clinicians noticed that the combination of low water content and high Dk resulted in improved comfort in patients who had previously experienced dryness in thin, high-water hydrogel lenses. My own clinical and research experience has shown that dryness symptoms decrease in both frequency and severity when hydrogel lens patients are refit into silicone hydrogels, even with extended wear.

Many practitioners perceive that silicone hydrogels are less comfortable than are hydrogels because of the increased lens awareness that results from higher modulus. So even if a patient's dryness symptoms improve, there is a trade off with more awareness of a stiffer lens. Silicone hydrogel manufacturers have combated this issue by introducing a newer generation of silicone hydrogel materials that includes lotrafilcon B (O₂Optix, CIBA), galyfilcon A (Acuvue Advance, Vistakon), and senofilcon A (Acuvue Oasys, Vistakon). These materials exhibit a lower modulus than the previous generation, which may result in improved comfort through reduced lens awareness. Both Acuvue Advance and Oasys contain Hydraclear, an internal wetting agent, which the manufacturer claims helps to maintain comfort and reduce dryness symptoms throughout the day.

I recommend silicone hydrogels to patients who complain of mild to moderate dryness. When appropriate, I educate them about an initial adaptation period of a few days to one week, but to then expect an improvement in comfort over the next several months. I don't expect patients who complain of significant dryness to be symptom free one week following a refit. I believe it takes several weeks for an inflamed ocular surface to improve following a refit into a silicone hydrogel lens.

Hydrogel Lens Options

I've also had good results using the hydrogel materials omafilcon A (Proclear, CooperVision) and hioxifilcon A (Extreme H₂O, Hydrogel Vision Corp.). Both utilize unique material properties that allow them to maintain a high water content throughout the wear cycle. At this time Proclear lenses are the only lenses to carry the FDA indication, "may provide improved comfort for contact lens wearers who experience mild discomfort or symptoms relating to dryness during lens wear."

These lenses may offer more immediate dryness relief with no adaptation period, although lower-modulus silicone hydrogels are closing the gap on initial comfort.

Taking Extra Steps

The etiology of dryness symptoms in lens wearers can be multi-factorial. Switching lens materials may not be enough to solve a patient's complaints. Carefully recommend not only the right material for each patient, but also a compatible disinfection system. Re-educate patients on lens care and hygiene, manage any lid disease and monitor the stability of the tear film to keep your patients comfortably wearing lenses.

Dr. Schafer is a clinical assistant professor and chief of the contact lens service at The Ohio State University College of Optometry.