LASEK, or Laser Assisted Subepithelial Keratomileusis, is a modification of the LASIK procedure for patients with very thin or very steep corneas. First, the outer layer of the cornea (the epithelium) is cut with a trephine. The trephine has a much finer blade than the microkeratome used in LASIK. Next, the eye is bathed in a special alcohol solution that loosens the edges of the epithelial flap. The flap is lifted so the central cornea may be exposed and treated with an excimer laser. After treatment, the flap is replaced and allowed to heal. A contact lens may be worn for a few days until recovery is complete.
More of the cornea is exposed for treatment with LASEK than with LASIK, making LASEK a better choice for patients who require greater vision correction. However, it also requires a longer recovery time.