Differences Between LASIK and PRK
This is a procedure in which the front surface of the cornea is directly sculpted by the excimer laser. The surgeon prepares the eye by gently removing the surface layer known as the corneal epithelium. This layer regenerates itself within a few days. As in the LASIK procedure, computer-controlled pulses are directed at the exposed surface (the corneal stroma) to reshape the cornea. Less than ten percent of the cornea is affected, with the deeper layers remaining untouched.
Photorefractive Keratectomy (PRK)
After the exposed corneal bed is treated by the laser and minute amounts of cells are vaporized, the flap is replaced in its original position. The flap is held in position by the eye's natural suction facility and natural sticky sugars, and provides increased comfort and decreased recovery time for the patient.
The LASIK procedure also uses the excimer laser to reshape the cornea, but this is done under a thin corneal flap, which preservers the surface epithelial cells. Rather than scraping away the epithelial cells to expose the corneal stroma as in PRK, a specialized surgical instrument known as a microkeratome (which works somewhat like a carpenter's plane) creates a flap of corneal tissue that is attached by a hinge. This flap is gently pulled back like a clear, hinged pancake and the corneal stroma is exposed. The laser part of the LASIK procedure takes place in the exposed corneal bed (corneal stroma). The laser application itself lasts about 30 to 90 seconds.
Laser In Situ Keratomileusis (LASIK)