Wednesday, October 22, 2014

Radial Keratotomy

Table of Contents

Definition

Radial keratotomy corrects myopia (near sightedness) with tiny incisions that flatten the cornea to change the way it focuses.

Keratotomy literally means "cutting the cornea." Radial keratotomy is similar to, but different from, newer forms of surgical change of the cornea such as LASIK.

Description

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.

Questions

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 LASIK (Laser in Situ Keratomileusis) be a preferred treatment?

Is there any alternative to surgery?