Radial keratotomy corrects myopia (short sightedness) with tiny incisions that flatten the cornea to change the way it focuses.
Keratotomy literally means "cutting the cornea."
The concept was pioneered in Japan some 50 years ago, when Japanese ophthalmologists observed that people who had accidental tears in the cornea tended to become less nearsighted as the tears healed. So the Japanese experimented with a primitive form of surgery, nicking the cornea with a series of tiny cuts. The Japanese method enabled patients to switch to weaker eyeglasses when it worked - but it often caused serious complications.
In people who are nearsighted, the eyeball is too long or the lens is too convex. As a result, light is focused slightly in front of the retina. Radial keratotomy can correct this condition by flattening the cornea to move the focal point back to the retina.
To achieve this, the ophthalmologist makes a series of tiny cuts in the cornea. The incisions radiate from a position over the outer edge of the pupil to the periphery of the iris, likes spokes of a wheel.
For mild cases, only four cuts may be needed; for more severe cases, eight or more incisions may be required to flatten the cornea adequately. The operation takes only a few minutes and is performed on an outpatient basis under topical anesthesia.
The procedure was popularized in the Soviet Union in the late 1960s. Because it could be performed with currently available surgical instruments, it was not subject to regulation by the Food and Drug Administration. However, because some of the earliest operations left the patient with worse vision than before surgery, the National Institutes of Health sponsored a large investigation called the Prospective Evaluation of Radial Keratotomy (PERK study), to determine if the procedure improved vision substantially when performed by the most experienced ophthalmologists.
The results indicated that it could. Five years after surgery, 80 percent of the patients in the PERK study had at least 20/40 vision - a degree of acuity considered acceptable for driving without glasses - and 60 percent had "perfect" 20/20 vision.
At the same time, the PERK study determined that the operation was not foolproof. Because no two corneas respond exactly the same way, doctors cannot be certain how the eyes will react under the knife. For example, older people's corneas flatten more with each incision than do younger people's.
The operation is not always an unqualified success. If the surgeon makes too many cuts, the patient will become farsighted. In the PERK study, this happened in 17 percent of cases.
More serious complications can occur. Some patients are left with hazy vision due to scarring as the cornea heals. Corneal infection and rupture are less common, but nonetheless possible. A small number of patients - less than 1 in 1,000 - sustain permanent vision loss after undergoing radial keratotomy.
Even when the procedure is deemed successful, many people still need glasses for distance vision. Contact lenses may no longer be an option, because alterations in the cornea can make them more difficult to fit.
Because radial keratotomy has no effect on the natural aging process, reading glasses are still often necessary for people in their 40s and beyond.
Unlike corrective lenses, the change radial keratotomy makes in your vision is permanent. If you are dissatisfied with the results, you cannot simply start over. If you are considering surgery, make an appointment with an ophthalmologist to see if you are a good candidate.
Do not hesitate to get a second opinion.
In general, you may be a good candidate for surgery if you:
- Have little or no astigmatism. An unequal curvature to your cornea means the surgery is less likely to eliminate your need for corrective lenses
- Do not require precise vision. Your vision following surgery may not be as accurate as with your glasses or contacts. For an electronics technician who works with tiny computer circuits, for example, surgery is not the right choice
- Are no more than 40 years old. As you age, your eyes are less able to compensate for some surgical complications. Your chance of needing glasses for reading also increases
- Are healthy. Conditions such diabetes and glaucoma increase risk of complications
- Have realistic expectations. The surgery does not always eliminate the need to wear glasses or contacts. Up to 3 people in 10 still may need some correction for distance.
How bad is the nearsightedness?
How do you choose a good candidate for radial keratotomy?
Will the vision improve; and to what extent?
Can you demonstrate with lenses what the vision will be after surgery?
Will glasses or contact lenses still need to be worn after radial keratotomy?
What are the possible complications of surgery?
Would newer laser surgery be a preferred treatment?
Is there any alternative to surgery?
