PRK and LASEK
Photorefractive keratectomy (PRK)
PRK is diopters to correct myopia up to about -5, used low-grade hyperopia and astigmatism. In more severe vision problems increases with the complication of PRK, so that it is not used there. At low and moderate vision problems, the PRC provides a very reliable procedure with few complications is.
In PRK, first the top layer of the cornea, called the epithelium mechanically removed. Next, by using an excimer laser is the center of the cornea modeled to the refractive error is balanced. After treatment, the epithelium forms from the margins in a few days new and covered the wound surface after a short time.
Laser Epithelial Keratomileusis (LASEK)
PRK is used for some time like in modified form as so-called LASEK.
The difference between LASEK to PRK is that away with LASEK the top layer of the cornea, the epithelium is not, but carefully replaced with an alcoholic solution such as a curtain is pushed back and after the laser treatment again placed over the wound. In general, therefore, the postoperative discomfort is reduced significantly and are comparable to those of LASIK surgery.
In the modified approach of the Epi-LASEK, the epithelium is not superseded by an alcoholic solution, but removed with vacuum and set aside. In principle it is similar but the LASEK.