Recent Onset Dry Eye . . .Why?

By Kelly A. Kinney, O.D., & Karla Zadnik, O.D., Ph.D.
MAR. 1997

What do you do when your previously successful RGP patient develops marginal dry eye symptoms? Reorder the same lens? Add ocular lubricants? Switch to soft lenses? Discontinue lens wear?

All of these are valid options. Our basic armamentarium for the dry-eyed contact lens wearer has been based largely on individual clinical experience. Clinical research has done little to give us concrete answers for treating these patients.

Problems associated with RGP lens wear and dry eye symptoms generally are related to lens wettability or an anomalous tear film. With appropriate testing, an adequate case history and careful lens inspection, we can minimize most dry eye symptomatology.

SURFACE WETTABILITY

Hazy or blurred vision, a gritty or dry sensation and lens awareness are all symptoms related to surface non-wetting. When evaluating an RGP lens, consider the material as well as the patient's lens care habits. Fluorosilicone acrylate lenses are more hydrophilic and tend to maintain an intact tear film longer than silicone acrylate lenses. Also, lenses with fluorinated monomers are less likely to bind protein, a finding common to the dry eye patient.

Many steps in the manufacturing process can produce non-wettability. Resins from the blocking process that are not thoroughly removed can lead to irregularities in the surface of the lens. Solvents can cause changes in the chemical structure of the materials, leading to a smudgy, non-wettable surface. You can help reduce initial lens irritation by carefully inspecting, cleaning and soaking the lenses prior to dispensing.

HANDLING CUES

Patient lens handling can also be the culprit in recent onset dry eye in the RGP patient. Many creams, soaps and cosmetics contain the skin-care supplement lanolin. If lanolin comes into contact with an RGP lens, it can leave a streaky smudge on the surface, producing irritation and decreased vision. Patients who use these products prior to handling their contact lenses can be contributing to dry eye symptoms. Recommend specially formulated optical soaps to help prevent surface contamination.

Patients with dry eyes tend to have a poor tear film, so debris is more likely to build up on the lens surface. Proper cleaning, soaking and enzyming is essential for the marginal dry eye patient. RGP lens cleaners that contain an abrasive surfactant are very effective in removing loose surface deposits secondary to cosmetics, residue from manufacturing, and greasy substances such as lanolin.

ANOMALOUS TEAR FILM

Dry eye, or keratoconjuctivitis sicca, is generally grouped into four categories: aqueous deficiency, mucin deficiency, lipid abnormalities and lid/surface abnormalities. To date, pinpointing anomalies in the tear film has challenged the clinician. In the past, clinicians have focused on the aqueous, while recent studies have examined the role of both the mucin and the lipid tear layers in maintaining the tear film. The techniques for measuring aqueous level, including the Schirmer tear test and the phenol red thread test, can be misleading. Marked staining of the ocular surface with either rose bengal or fluorescein dye is present in only the worst of cases.

The best way to diagnose marginal dry eye is to compile a well thought-out case history of patient symptoms in combination with a thorough slit lamp examination of the lids and ocular surface. Treat any signs of blepharitis or meibomian gland dysfunction with lid hygiene and medication. Note any medications the patient may be taking, especially new medications, and discuss any changes in the environment or the day-to-day routine that may affect contact lens wear. Adding ocular lubricants to a proper lens-care regimen is beneficial to the dry eye patient.

AM I SHERLOCK HOLMES?

With a little sleuthing and a careful examination, you will uncover many clues to the origin of the dry eye problem. If you rule out non-wettability, improper lens care and tear film anomalies, then you may need to change lens material or type, or in the worst case, reduce or discontinue lens wear. Approach all your options in a step-by-step fashion. Patients will appreciate your efforts to be an RGP problem-solver on their behalf. CLS

Dr. Kinney is a graduate student in physiological optics at The Ohio State University College of Optometry in Columbus. Dr. Zadnik is an assistant professor at OSU.