contact lens Q&A

Confronting Some Common Contact Lens Queries

JAMES V. AQUAVELLA, MD
FEBRUARY 1998

The scope of contact lens practice incorporates much more than prescribing contact lenses to correct ametropia in otherwise normal, healthy eyes. Today's contact lens practitioners are confronted with a variety of confronted with a variety of situations that may generate some debatable questions. Below are a few of the common ones.

A number of my patients wear their daily disposable contact lenses for several days instead of disposing them upon removal. Is this advisable?

ANSWER: The polymers currently marketed for daily disposal are equivalent to those routinely used for daily wear with planned replacement at weekly to monthly intervals. Oenses marketed as "daily disposable" means the manufacturers are able to produce a large number of lenses, dramatically reducing the per-lens cost. Many patients have tried to save money by wearing these lenses for much longer periods of time. Provided that patients clean and disinfect the lenses properly and avoid wearing them overnight, there's no theoretical limit to their use. As long as comfort and good acuity are maintained, daily disposable lenses can be worn in a manner that best suits the patient's lifestyle and pocketbook. All things being equal, however, a fresh, new contact lens is most desirable.

I've been told that patients must discontinue contact lens wear for three weeks before being evaluated for excimer laser PRK. Is it necessary to repeat this process before treatment?

ANSWER: It's important to have stable baseline refractive data when evaluating patients for any refractive surgical procedure. Clearly, the eye should be stable before performing the procedure as well. While corneal curvature changes can occur for weeks after removing PMMA contact lenses, stability is usually achieved only a few days after removing RGPs. Soft contact lenses with relatively less oxygen permeability should be removed for approximately one week.

How soon following corneal transplantation should a patient be fitted for contact lenses?

ANSWER: There's no real consensus among corneal surgeons in this matter. If the eye is white and quiet, the sutures have epithelialized and the patient requires a contact lens in order to function, you can fit an RGP as soon as one month following surgery. If the patient has good acuity in the fellow eye and is able to function, there's very little to be gained by fitting a contact lens until all of the sutures have been removed. When the graft has healed completely and the sutures are removed, the cornea will remain unstable for several weeks. In fitting a definitive contact lens following suture removal, I like to have the benefit of two successive evaluations, such as refraction and keratometry, conducted two weeks apart. If acuity and corneal curvature remain stable, you can prescribe RGP or soft lenses. It is not unusual, however, for minor changes in curvature to proceed for several months.

What medications can be instilled in the eye while contact lenses are in place?

ANSWER: A significant percentage of patients instill artificial tears while wearing their lenses (soft and RGP). Most prescription medications can be safely instilled over an RGP lens without damage to the lens, but soft lenses may be adversely affected. A contact lens, either RGP or soft, will clearly interfere with the penetration of any drug through the corneal epithelium and into the anterior chamber. In general, it's wise to advise instillation of all prescription medications prior to insertion of the lens in the morning and following removal of the lens in the evening.

Dr. Aquavella is chairman of the Genesee Valley Eye Institute and director of the corneal research lab at the University of Rochester.