How LASIK Works
Most normal vision problems occur because the lens in the front of the eye (your cornea) is not focusing light correctly on the back of the eye (your retina) where light is changed into the nerve signals that are sent to your brain and allow you to see.
LASIK corrects for three common eye conditions by reshaping the cornea so that the light entering the eye will focus better on the retina. The method differs for each condition, as detailed below:
Hyperopia (farsightedness): To correct farsightedness, the central cornea must be made steeper. This is achieved by directing the laser beam to remove tissue from around the central cornea.
Myopia (nearsightedness): To correct nearsightedness, the cornea must be made flatter. This is achieved by removing tissue from the center of the cornea.
Astigmatism: To treat astigmatism, the cornea must be made more round. This is achieved by removing more tissue from one part of the cornea than another.