But, many others still feel skittish about the risks and permanence of laser procedures. Now, they have a third choice, say doctors at the University of Michigan Health System. The new procedure, available at the U-M's Kellogg Eye Center and other select locations since early 1999, fixes eyesight by implanting a tiny plastic ring into each eye. After several months of seeing the results for themselves, U-M eye surgeons say the quick, effective and reversible operation could provide a needed alternative for about half of all nearsighted people. The implants are called corneal rings.
Nearsightedness is caused by corneal steepness, or increased length of the eye.
As a result, the eye bends, or refracts, light incorrectly and focuses it before it reaches the retina. Both the corneal rings and laser procedures underwent extensive testing before gaining approval from the Food and Drug Administration and becoming widely available. The first corneal ring implant to be approved is Intacs, made by Keravision . Studies of corneal rings showed they can be adjusted or removed without adverse affects. On the other hand, the rings can only help those patients whose nearsightedness falls within minus one to minus three diopters, or optical measurement units.