Surgery can be used to reshape the cornea and correct some refractive errors permanently. The main techniques are laser in-situ keratomileusis (LASIK), laser epithelial keratomileusis (LASEK), and photorefractive keratectomy (PRK). In LASIK, a cut is made across the cornea to create a flap, the middle layers of the cornea are reshaped by laser, and the corneal flap is replaced. LASEK is similar to LASIK but cuts less deeply into the cornea. In PRK, areas of the surface of the cornea are shaved away by laser to alter the cornea’s shape.
From the 2010 revision of the Complete Home Medical Guide © Dorling Kindersley Limited.