Eye Surgery Helps Some See Better

by Food and Drug Administration (FDA)

"Men seldom make passes at girls who wear glasses," Dorothy Parker observed in 1926. True or not, when the writer penned her now famous line, the only alternative to glasses was poor sight. Things are rosier — but not perfect — at the close of the century.

Today, growing numbers of women and men alike are opting for refractive eye surgery to correct their myopia (nearsightedness) in hopes of abandoning their glasses or contact lenses. The most common procedure is called radial keratotomy, or RK, and the National Eye Institute says about 250,000 are done each year in the United States, up from 30,000 in 1990.

Another surgery, newly available in the United States, is photorefractive keratectomy, or PRK. In October 1995, the Food and Drug Administration approved the Summit Apex excimer laser system for use in this procedure. A report by the American Academy of Ophthalmology published in the July 7, 1993, issue of Ophthalmology indicates that cosmetic reasons are not at the top of the list of reasons why people choose to have refractive surgery. The report states: "In two studies, approximately 75 percent of the patients who were interviewed about their reasons for seeking radial keratotomy stated that they wished to see well without physical dependence on ... spectacles or contact lenses. Patients also sought radial keratotomy to improve their performance in profession or sport, to improve cosmetic appearance, for simple convenience, or at times to meet the visual requirements for occupations such as law enforcement and firefighting."

David Euley, a 52-year-old Darnestown, Md., kitchen designer and home remodeler, began to consider RK when he found himself becoming increasingly frustrated with his glasses, particularly at work. "It was difficult to go back and forth from blueprints to taking measurements to working on a computer," he says, adding that he needed a separate prescription for computer work.

Euley talked with several ophthalmologists before deciding to have the surgery last December. Interviewed four months later, he was delighted with the results: "This is the first time in 25 years I've been able to see the titles on television without glasses. I can read license plates. I can see the deer in my backyard. And my glasses are sitting on a shelf somewhere."

Six incisions in each cornea (the clear part of the front of the eye) left Euley with uncorrected vision improved from 20/800 in both eyes to 20/20 in the right and 20/25 in the left. (A person with 20/40 vision, for example, would see an object from 20 feet that another with perfect vision — 20/20 — could see at 40 feet. Some people see even better than 20/20.)

RK is often done in the doctor's office. As in Euley's case, surgeries on each eye are usually scheduled a few weeks apart, as a precaution in case there are complications. The patient is given anesthetic eye drops to numb the eye. Using a high-precision diamond blade knife, the surgeon makes from four to eight spoke-like incisions in the cornea, while the patient focuses on the light of the operating microscope. The surgery takes about 10 to 15 minutes.

I Can See Clearly Now

Euley can read those license plates without glasses now because the incisions changed the shape of his corneas. Normally, the cornea and lens bend light rays to focus directly on the retina — the tissue at the back of the eye that receives the image. If the cornea or lens is too rounded, or the eyeball is elongated, the light focuses in front of the retina, blurring distant objects. RK reduces or eliminates the myopia by flattening the cornea and redirecting the light to focus on the retina.

The patient may have some pain or discomfort for 24 to 48 hours after surgery, possibly requiring medication. Glare, starbursting, or a halo effect, especially at night, is common for a few months and occasionally persists a year or more. Vision also commonly fluctuates during the day, with acuity best in the morning and diminishing somewhat at night. This decreases in severity during the first year, but may last for many years.

Notwithstanding some claims to the contrary, RK is not a cure-all. (The Federal Trade Commission is investigating the problem of misleading claims in advertisements.) Reputable ophthalmologists will tell prospective patients the procedure is not completely risk-free, and perfect vision cannot be guaranteed.

Is RK Safe and Effective?

"FDA does not regulate radial keratotomy because it is a medical procedure, not a medical device," says Emma Knight, an ophthalmologist and medical reviewer with FDA's Center for Devices and Radiological Health. "The knife used in RK had been cleared by the agency for general corneal surgery."

The National Eye Institute (NEI), however, concluded from a 10-year study called "Prospective Evaluation of Radial Keratotomy (PERK)" that RK is "reasonably safe and effective … with serious complications being rare."

All patients in the study had -2 to -8 diopters and could be corrected to 20/20 vision or better with glasses or contact lenses. (A diopter is the unit of measurement of spectacle or contact lens power. A minus value indicates nearsightedness; plus indicates farsightedness, or hyperopia. Euley's correction was -3.25 diopters.)

Results of the NEI-sponsored multicenter trial were reported by study investigator George Waring III, M.D., and colleagues in the October 1994 Archives of Ophthalmology. Among 374 patients (with 693 operated eyes) who returned for the 10-year follow-up:

• 70 percent said they did not wear glasses or contact lenses for distance vision.
• 53 percent had 20/20 vision without glasses.
• 85 percent had at least 20/40 vision without glasses — the acuity most states require for driving without glasses.
• Of the total 793 eyes operated (including data from the most recent examination of those who didn't return for the 10-year follow-up), 143 lost one line of best spectacle-corrected vision on the standard eye chart, 19 lost two lines, and four lost three lines. (Best corrected vision in all but 16 eyes was 20/20 — they previously had better than 20/20 corrected vision. Thirteen eyes were corrected to 20/25 and three to 20/30.) This means that, although eyesight without glasses was improved from pre-surgery acuity, residual nearsightedness could not be corrected with glasses to pre-surgery acuity.
• 38 percent of patients were corrected within one-half diopter of the predicted result; 60 percent were within 1 diopter.
• 43 percent developed "hyperopic shift" — a gradual change toward farsightedness (1 or more diopters between 6 months and 10 years) at a younger age than would be expected.

About the Author

www.fda.gov
FDA is A United States government body that oversees medical devices, including contact lenses, intraocular lenses, excimer lasers and eyedrops. In the US, these products must be approved by the FDA before they can be marketed.