Laser action (photo-ablation, that is to say reshaping the cornea so as to modify the radii of curvature and thereby correct the visual disorder) is carried out on the surface of the cornea following removal of the epithelium. In PRK, the epithelium is manually removed, in some cases using an alcohol solution.
In the late 1980s, PRK was the first laser technique to be used as a means of correcting visual disorders.
This technique facilitates treatment of fine and/or suspect corneas. Its indications go hand in hand with contraindications for Lasik, which is more comfortable for the patient. The advantages of PRK reside first in the absence of the risk associated with laser cutting, and second in its maintaining a superficial photo-ablation allowing for preservation of corneal thickness (“anterior stromal bed”). On the other hand, post-operational effects are of longer duration, and pain may persist during the 48 hours following surgery (application at the conclusion of the operation of a bandage lens that will not be removed prior to the third day after), while visual recovery seldom occurs prior to the fourth day after. In terms of patient comfort, Lasik is to be preferred when possible (discomfort limited to a few hours, visual recovery in less than twelve hours).