Photorefractive Keratectomy (PRK) was the first laser technique approved by the FDA (Food and Drug Administration) and VISX was the first company to receive approval to correct refractive eye problems using the excimer laser. Currently, the VISX laser has 60% of the market and is the laser used by our office.

A drop of anesthetic is placed upon the eye to be treated and the painless procedure takes an average of 1-3 minutes. A "cold" laser called an excimer laser, corrects the focusing power of the eye by sculpting a very thin layer of tissue on the surface of the cornea (clear window at the front of the eye) to make the front curve of the cornea flatter for nearsightedness and steeper for farsightedness.

To correct astigmatism, the laser beam changes the curves on the cornea to make the points of light focus simultaneously to a point on the retina of the eye. The excimer laser actually uses ultraviolet laser light pulses with an accuracy of approximately one-millionth of an inch, to correct the surface curvature of the eye. The entire procedure is done in an outpatient setting and is bloodless with no cutting or sutures required.

"Following laser vision correction best uncorrected vision may improve more slowly with PRK and there may be more discomfort than with LASEK or LASIK. Generally, following the PRK procedure a bandage soft contact lens is placed on the eye for the first 72 hours for comfort. Patients with myopia and astigmatism of less than -6.00 diopters have final vision equal to that achieved with LASIK or LASEK. (See discussion below)

With PRK or LASEK there is less thinning of the cornea than with LASIK because the laser treatment starts on the stromal surface (the layer below the surface epithelial layer) of the cornea after the epithelium is removed. Because the laser treatment starts on the surface, more stromal corneal tissue can be safely removed with PRK and LASEK (see below) allowing higher degrees of nearsightedness to be treated than with LASIK.

However, PRK treatment of patients with high degrees of nearsightedness (over -6.00 to -8.00 diopters) has a higher risk for the development of haze or clouding of the cornea which may be permanent. The use of mitomycin has been shown to reduce or prevent this haze for patients having high degrees of nearsightedness with the surface laser treatments PRK or LASEK. Mitomycin is an antibiotic which is applied to the cornea immediately after the laser treatment is performed to prevent haze or scarring. It is important to realize that haze and scarring can occur with any type of laser treatment and the risk does increase for higher degrees of nearsighted error.

© Earl W. Nepple, M.D., 2003 - All Rights Reserved
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