For people born with normal vision, light passes through the cornea and focuses directly on the retina at the rear of the eye, producing clear vision.
If you wear contact lenses or glasses, you're physically unable to focus light on your retina. You have a vision error, typically genetically determined.
There are three primary vision errors, each the result of an eye shape that differs specifically from that of a normal eye. These errors include nearsightedness (myopia), farsightedness (hyperopia), and astigmatism. (A fourth error, called presbyopia, causes a loss of reading vision, for which a laser vision correction technique, called monovision, can compensate).
A nearsighted, or myopic, eye is longer in the cross section than a normal eye, causing light to focus in front, rather than on, the retina, blurring your distance vision (see animation below).
Dr. Hyver can use either LASIK or PRK to correct nearsightedness. He does so by using the laser to slightly flatten your cornea, thus moving the light's focal point onto your retina, producing clear vision, free of your contact lenses and glasses.
The following animation illustrates nearsightedness.
