LASIK - Methods

For a normally seeing eye, entering light is refracted by the cornea and lens in such a way that a sharp image is created on the retina. If the focus point does not lie on or is not focused on the retina, the refractive power is disrupted - one would refer to this as a refractive error. Three fundamental types of refractive errors can be distinguished: nearsightedness (myopia), farsightedness (hyperopia), and irregular curvature of the cornea (astigmatism).
In realm of refractive surgery, whose goal is the operational correction of refractive errors, such eyesight failures can be addressed through various surgical methods. The goal of these surgical methods is a precise calibration of the retina for the purpose of influencing the refraction of incoming light. The four most common methods are:

1) LASIK (Laser in situ Keratomileusis): A microkeratome is used to make an incision in the cornea, opening the way to the inner cornea; subsequent tissue abrasion (ablation) is accomplished via laser radiation.

2) Femto-LASIK (intralasik): No incision is made using a microkeratome; correction is undertaken using two different lasers.

3) LASEK (Laser-Assisted Subepithelial Keratectomy): The epithelium (a thin layer of tissue on the surface of the cornea) is temporarily peeled away and opened; the tissue abrasion takes place on the surface of the cornea.

4) PRK (Photoablative Refractive Keratectomy): The epithelium is removed and tissue abrasion via laser radiation takes place on the corneal surface.