Laser Vision Correction

Refractive Surgery is a term for several procedures designed to treat 'refractive errors' such as nearsightedness, farsightedness, and astigmatism. The goal of refractive surgery is to reduce or eliminate dependence on corrective lenses. Although the vast majority of patients see 20/40 or better postoperatively, individual results cannot be guaranteed. Patients over 40 years old who have surgery to treat nearsightedness may find they need reading glasses for close work after surgery. Refractive Surgery is performed on an out-patient basis and most people return to work within one to three days.

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Radial Keratotomy (RK) is most effective at treating low to moderate levels of nearsightedness. It was first attempted in the 1970's by a Russian physician named Fyodorv. He discovered that placing a number of microscopic, spoke like incisions, in a "radial" pattern around the center of the cornea caused it to flatten. This flattened shape allows light to focus more directly on the retina, thereby reducing or eliminating nearsightedness.

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Astigmatic Keratotomy (AK) is simply a modification of the Radial Keratotomy technique and is often performed on patients who have both nearsightedness and astigmatism. To treat astigmatism, the cornea must be made more spherical, or uniformly curved in all directions. This is accomplished by making incisions in the steepest part of the cornea, causing it to relax and become more round. AK can be performed along with other types of refractive surgery, too.

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Excimer Laser

In the early 1980's, researchers found that IBM's new Excimer laser, used initially for etching computer chips, had refractive surgery applications as well. Unlike other lasers that tend to damage surrounding tissue, the "cool" light from the Excimer laser created no thermal damage to surrounding tissue and left a very clean margin.

Ultraviolet light and high energy pulses lasting only a billionth of a second disrupt the molecular bonds between the corneal cells with accuracy up to 0.25 microns. The beam of the Excimer light is so fine it would take over 200 pulses to etch through a single strand of human hair.

The first Excimer laser procedure to treat nearsightedness was done in 1988. Since those early days, the Excimer laser has undergone many refinements. Excimer laser technology has added more precision and predictability to altering the shape of the cornea and is now being used to treat nearsightedness, farsightedness and astigmatism in every advanced country around the world.

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Photo-Refractive Keratectomy (PRK) uses the Excimer laser to treat low to moderate amounts of nearsightedness, farsightedness and stigmatism. First the epithelium, a thin layer of protective skin, is removed. Next, the Excimer beam is directed to reshape the corneal surface so that light rays will focus more directly on the surface of the retina. The amount of tissue to be removed is determined by the amount of nearsightedness, farsightedness or astigmatism to be treated. For most patients, only five to ten percent of the cornea is removed to obtain the desired results.

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LAser in-SItu Keratomileusis (LASIK) can be used to treat low to severe levels of nearsightedness and moderate amounts of farsightedness and astigmatism. LASIK combines the computer controlled precision of the Excimer laser with the faster healing benefits of another type of refractive surgery called Lamellar Keratoplasty.

While PRK treats the surface of the cornea, LASIK treats the inner tissue of the cornea. First an instrument known as a microkeratome makes a flap in the outer layer of the cornea, at about twenty-five percent of its depth from the surface. The flap, which remains attached on one side, is then folded back. Next, the Excimer laser sculpts the internal corneal tissue to the desired shape. The corneal flap is laid back in its original position where it is allowed to dry for a few minutes. Due to the cornea's extraordinary natural bonding qualities, stitches are usually not required. LASIK results are usually realized sooner than with PRK.

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