Discovering dry eye

Managing Low-Level Dryness in Hydrogel Patients

BY CHRISTOPHER SNYDER, OD, MS
FEBRUARY 1999

asoft lens wearer's minor, periodic drying symptoms can be a diagnostic challenge when you find no clinical signs of tear deficiency problems.
Below are some possible sources of symptoms of dryness contact lens-related dryness.

Aqueous Tear Deficiency

Dehydration of a hydrogel polymer is typically the first and foremost culprit that comes to mind when a patient reports dryness with lens wear. So, patients with aqueous tear deficiency (ATD) should not be fitted with soft lenses (Figs. 1 & 2). ATD is usually caused by a primary dysfunction of the lacrimal gland, or it may be secondary to a systemic disease, typically autoimmune varieties such as rheumatoid arthritis and Sj�gren's syndrome.

FIG. 1: Normal lower lid margin tear meniscus.

FIG. 2: Insufficient lower lid margin tear meniscus.

Cellular Changes

Besides aqueous volume, other tear components help maintain the ocular surface and the lens. Normal meibomian gland secretions support the superficial lipid layer of the tear film and retard aqueous evaporation, while the goblet cells of the conjunctiva provide the mucin layer for wetting and maintenance of the ocular surface cells. Microscopic changes within the conjunctival epithelial cells, similar to those seen in ocular surface diseases, have been found in symptom-free hydrogel wearers. It's possible that these subclinical levels of cellular change can progress to the point of causing the vague discomfort of nonspecific dryness.

While it is not known what actually causes such surface cell changes, mechanical effect of the soft lens on the conjunctival cells is the leading suspect. Changing the lens material or fit may help.

The Lens Care Culprit

Another possibility for lens related dryness is the patient's lens care product. Multipurpose products include many components in one solution for cleaning, rinsing and disinfecting. The ingredients also often include a surfactant, which may destabilize the tear film and disrupt the membrane of the ocular surface cells. If patients in these vague cases are using multipurpose solutions, consider changing them to a preservative-free, non-multipurpose lens care system or to a different brand of multipurpose system. This is an easy initial differential diagnosis step before entertaining the more involved (i.e., refitting) or patient-intensive (i.e., increased use of rewetting drops) actions.

Table 1 lists some options to seek out and destroy the source(s) of drying symptoms.

Dr. Snyder is a professor of optometry and serves as chief of contact lens patient care at the School of Optometry at the University of Alabama at Birmingham.