Prescribing for Presbyopia
Determining the Cause of Lens-Related Dryness
BY CRAIG W. NORMAN, FCLSA
When I see a contact lens patient who has dry eyes, I always ask myself this most fundamental question—is it the patient, the lens, or the lens care system that is causing these symptoms?
Is it the Patient?
Demographically, due to age and gender (contact lens wearers are mostly women), presbyopic patients often present with subjective complaints of lens awareness, decreased wearing time, itching, burning, and variability of vision—each of which might be related to lens-induced dry eye.
We find that tear quality/quantity tests and patient questionnaires prior to fitting are helpful as a predictor of potential dry eye issues, although even patients who have normal tear tests can have ocular surface wetting issues. For instance, there is increasing evidence that lid-wiper epitheliopathy is present in up to 80 percent of patients who have no clinical signs, yet describe dry eye symptoms. Thus, a close analysis with fluorescein of the marginal conjunctiva of the upper lid margin should be considered before fitting or at least if a patient is describing dryness while wearing contact lenses.
We also closely investigate the systemic medications being used and quiz patients on their daily environmental conditions to ensure that these are not playing a role in the dryness symptoms.
Don’t forget ocular allergies. Either the patient’s allergies or the associated medications can cause dry eye symptoms.
Is it the Lens?
Obviously, the contact lens itself can be complicit in lens-induced dryness. More often it’s the contact lens material rather than the lens design.
For multifocal soft lens wearers, material characteristics such as surface wetting, dehydration, water content, and resistance to deposits and films are important. Newer silicone hydrogel polymers are showing improvements with these lens characteristics by keeping water content low but maintaining hydration while providing good wetting and interaction with tears. GP materials are achieving the same, and most multifocal and bifocal GPs offer the option of plasma surface treatment, which keeps the surfaces cleaner to result in less deposits and improved comfort.
What About Lens Care?
For sure we need to bring lens care systems into this discussion. If the symptoms of dryness are occurring early in the daily wearing time, the lens care system may be the culprit. Changing lens care systems, for instance from multipurpose to hydrogen peroxide, is one way determine the impact of lens care.
Alternatively, I prefer switching to a daily disposable when confronted with a possible solution reaction, although at this time there are limited options in presbyopic soft lenses in this category. Luckily, new single-use soft multifocal contact lens introductions are expected in the very near future.
Do a Little Detective Work
You need to be a contact lens detective to determine which of these areas is the cause for an individual patient’s lens-induced dryness. You may need to look at all three to consider the best alternative for a given patient. CLS
Craig Norman is director of the Contact Lens Section at the South Bend Clinic in South Bend, Indiana. He is a fellow of the Contact Lens Society of America and is an advisor to the GP Lens Institute. He is also a consultant to B+L. You can reach him at email@example.com.