How to Treat Contact Lens-Related Dry Eye
CL and dry eye
How to Treat Contact Lens-Related Dry Eye
Demographics, environment, general health, lens systems and motivation all play a role.
JUDY HASDAY contributing editor
For the patient who desires contact lens wear, dry eye can be a minor hindrance or so problematic as to be considered a contraindication for contact lens wear. Several numbers offer us a "Big Picture" perspective on this challenge:
• According to the Schepens Eye Research Institute at Harvard University, about six million women and three million men in the United States have moderate to severe symptoms of Dry eye disease (DED), with an additional 20 million to 30 million experiencing mild cases of dry eye.
• Contact lens manufacturers report 34 million people wear contact lenses in the United States.
• Wearing contact lenses, even hydrophilic lenses, can increase the evaporation of tears, says a study by William Mathers, M.D., published in the March 2004 issue of Experimental Eye Research.
It's essential to first diagnose the degree of dry eye and determine whether the patient is a candidate for contact lens wear.
"Assessing [their] motivation for wearing lenses and having a careful discussion about the meaning of ‘success,’ as it applies to this fitting scenario," is the best way to begin, according to Gregg Russell, O.D., of the Marietta Eye Clinic in Georgia.
Ernest Bowling, O.D., director of VisionAmerica, Gadsden, Ala., concurs. "A highly motivated patient often overcomes a lot of ills," he says. Dr. Bowling adds he believes another component in a successful outcome in contact lens wear is making the patient aware of the dry eye signs and cautioning that these signs may cause a future problem.
ILLUSTRATION BY ANDREW PINKHAM
Understand your history
Whether the patient is a first time or existing contact lens wearer, the first step in assessing the appropriate fitting process starts with the patient history.
Has the patient ever tried contact lenses in the past? says Dr. Russell, "Many times, important clues can be gleaned about materials and solutions that can turn failure into success. The examination is centered on careful evaluation of anatomy — does the patient blink accurately and often? Are the eyelid aperatures too wide? What is the horizontal visible iris diameter? Are there significant pinguecula or other ocular surface issues? Does the patient show signs of papillary changes under the lid related to allergy? Do we need to consider the consequences of material choices (silicone hydrogel vs. hydrogel?) Which care system should be used— peroxide or one-step?
Find the cause
Many causes play a role in the development of dry eye. Often, the causes are associated with the presence of systemic diseases, including rheumatoid arthritis, Sjogrens Syndrome, thyroid dysfunction and multiple sclerosis. Dry eye can also be a side effect of medication use, such as those used to treat allergies (antihistamines and nasal decongestants), some blood pressure drugs, antidepressants and birth control pills. Menopausal women prescribed estrogen alone as hormone replacement therapy are 70% more likely to develop dry eye.
Age and gender also seem to play a part in the incidence of dry eye. According to a Women's Health Study, five million U.S. men and women older than age 50 have dry eye syndrome, and the incidence of dry eye in women is almost two times that of men.
Also, environment or viewing habits can contribute to dry eye. Windy, dusty, or dry climates aren't ideal conditions for contact lens wear. People who often spend hours in front of a computer screen blink less often, reducing the frequency of tear film distribution to the cornea.
Many doctors, such as Paul Karpecki, O.D., of Koffler Vision Group in Lexington, Ky., use the Tear Film Breakup test. "A reading under 7 is considered a dysfunctional tear film, although I often see that measurements under 5 are usually indicative of patients being symptomatic and having problems with CL wear," he says.
Milton Hom, O.D., of Azusa, Calif., prefers to use Pre lens tear thinning time (PLTTT), a method to quantitate tear film stability relative to symptoms of dryness. A study of 32 subjects measured for PLTTT, suggested that a PLTTT breakup time of less than 3.0 seconds might be a suitable criterion for tear film dysfunction, causing dryness symptoms.
Once you've determined the degree of dry eye isn't so severe as to eliminate contact lens wear as an option, take time to evaluate which contact lens product is best to prescribe.
"Much of this depends on the goal of the fitting and a clear understanding of materials, solutions and lens powers," says Dr. Russell.
Dr. Karpecki cited several studies that indicate that low water content lenses might be a good choice when deciding on a lens for the dry eye patient. "There are studies where low water content lenses appear to remain hydrated for a longer period than high water content lenses. Non-ionic, low water content lenses show a statistically significant improvement in a number of subjective parameters, including comfort, dryness, frequency of eye irritation and frequency of burning." In addition, Dr. Karpecki mentions that some anecdotal reports suggest that daily disposable lenses, because of less build up of proteins, will likely help patients who have dry eye.
Beyond the lens
Aside from lens choice, punctal plugs and various medications can offer the patient relief from dry eye and the increased symptoms and irritation caused by contact lens wear. For poor aqueous production, a popular choice among practitioners is cyclosporine (Restasis, Allergan). Also, many practitioners prescribe rewetting drops. In addition, doctors recommend checking for evidence of posterior blepharitis, and, whether present, prescribing therapy.
Further, studies support punctal occlusion. And, limiting wear based on environmental factors or while performing certain tasks — such as mowing the lawn during allergy season — may help minimize dry eye irritation exacerbated by CL wear.
Perhaps the best way to eliminate contact lens-related dry eye isn't one thing but rather a combination of things.
"I think setting goals and picking the right combination of materials gives the best outcome," says Dr. Bowling. "This might mean that the patient has to pick their battles and wear lenses at specific points if their dry eyes are particularly bothersome." OM
|Judy Hasday is a freelance writer/editor based in the Philadelphia area.|
Optometric Management, Issue: April 2009