THE EXCIMER LASER - PROCEDURES

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PRK for Myopia.

PRK for Hyperopia.

The excimer laser is utilized for two primary refractive procedures. Historically the first procedure was PRK. PRK uses the laser to gently reshape the outer surface of the cornea. Deeper cell layers remain virtually untouched. The laser can precisely reshape the cornea of the eye in seconds. This reshaping enables light rays entering the eye to focus onto the retina, resulting in clearer vision. Since the laser removes only a very thin layer of the cornea, the cornea keeps its original strength. PRK can be used for mild to moderate myopia, hyperopia, and astigmatism.

LASIK for Myopia. LASIK for Hyperopia

A second excimer laser procedure is LASIK. LASIK combines the precision of the excimer laser with a procedure that has been performed manually for over 40 years. The benefit of LASIK is that it can provide people with severe and extreme cases of myopia, hyperopia, and astigmatism with more successful results. Both procedures will be described in more detail in a separate section. LASIK is used for all levels of myopia, hyperopia, and astigmatism (mild, moderate, and severe).

Calibration of this laser is done on a special plastic card. The computer is directed to cut a -4.00 diopter sphere, a - 4.00 diopter cylinder, a +4.00 diopter sphere, and a plano cut in the special plastic card. The powers of these plastic lenses, cut on the plastic card, are read on a lensometer. If the measured powers deviate from the intended powers, the gas mixture and or voltage of the laser cavity is adjusted to set the energy output of the laser to the appropriate amount so that the measured power of the plastic cuts are correct. There is simply no other laser that can be calibrated like this. This calibration is done prior to treating each patient to attain the best possible results for each person.

The VISX STAR S4 laser is the most sophisticated excimer laser on the U.S. market today. It creates the smoothest sculpting of any laser sold today. Cuts in plastic result in smooth featureless surfaces compared to other lasers. This results from the scanning system of the beam homogenizing module. The smoother the sculpting, the better the clinical results. This has been confirmed by comparing clinical results on hundreds of patients.

When the smooth scan STAR S4 is used for PRK the epithelium grows back faster because the corneal stromal surface is smoother. The uncorrected and best corrected visual acuity is better. When the smooth scan STAR S4 is used for LASIK the uncorrected and best corrected visual acuity is better.

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