PRK, PARK, LASIK

PRK was invented in the early '80s. The first FDA approval of a laser for PRK was in 1995, but the procedure was practiced in other countries for years. In fact, many Americans had the surgery done in Canada before it was available in the U.S.

PRK is performed with an excimer laser, which uses a cool ultraviolet light beam to precisely remove ("ablate") very tiny bits of tissue from the surface of the cornea in order to reshape it. When you reshape the cornea in the right way, it works better to focus light into the eye and onto the retina, providing clearer vision than before.

Both nearsighted and farsighted people can benefit from PRK. With nearsighted people, the goal is to flatten the too-steep cornea; with farsighted people, a steeper cornea is desired. Also, excimer lasers can correct astigmatism, by smoothing an irregular cornea into a more normal shape.

The doctor uses a computer to adjust the laser for your particular prescription. You will be asked to look at a target light for a short time while he or she watches your eye through a microscope to adjust the laser for your particular prescription. You will be asked to look at a target light for a short time while he or she watches your eye through a microscope to make sure it remains in the correct position while the laser sends pulses of light to your cornea that painlessly remove the tissue. It's important to keep your gaze fixated on that target light in order to get the best results.

The laser machine will make a steady clicking sound while the laser pulses are happening, and you may smell a faintly acrid odor during the tissue removal. Don't worry, that's normal.

The higher your prescription, the more time the surgery will take.