Introduction

Laser and LASIK procedures for vision correction are performed in individuals who wear glasses and wish to replace them for various reasons. People suffering from nearsightedness (myopia), farsightedness (hyperopia), and astigmatism are candidates for these procedures. These conditions are referred to as refractive errors. In these patients, due to the refractive disorder of the eye, a clear image of distant or close objects does not form on the retina. Laser procedures correct these refractive errors, serving the function of glasses and compensating for this deficiency. Even individuals with presbyopia can undergo these procedures, although it is still uncertain whether these patients can reliably be considered candidates for surgery.

These procedures are performed on the cornea of the eye, and the shape alterations made to the cornea help focus and clarify the image in the eye. The procedures consist of two phases: In the first phase, the surface layer of the cornea, known as the epithelium, is removed (PRK), or a thicker layer called the flap is separated from the cornea (LASIK). In the second phase, using a specialized laser device called an “excimer” laser, desired changes are made to the cornea. Although the final stage of all these procedures is carried out using a laser, the preparation of the cornea is done through different techniques, and the procedures are usually named based on the first stage of the operation.