PRK stands for photorefractive keratectomy, treats mild to moderate myopia, hyperopia, and astigmatism. PRK uses a cool beam of ultraviolet light to reshape the cornea.  Unlike with LASIK, there is no flap in the cornea.  There may be slightly longer healing time with PRK compared with LASIK.  However the results are also excellent and PRK may be a more suitable option for patients with thinner corneas.