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.
The first step in LASEK is to remove the epithelium, a thin layer protecting the cornea. Then the surgeon uses an excimer laser to vaporize a small amount from the top of the cornea. LASIK, by contrast, cuts a deep flap in the cornea using a sharp microkeratome blade. This weakens the cornea, makes it difficult to replace the flap in precisely the right place, and can cause other complications including flap irregularity, epithelial ingrowth and corneal ectasia. LASEK avoids these risks.
Studies have shown that 90-95% of patients with a correction of up to -6.00 diopters achieve vision of 20/40 after LASEK, and up to 70% achieve 20/20. Patients needing less correction generally achieve better results. The risks of LASEK include infection, haze, slow healing, scarring, over- or under-correction of the visual condition, and development of astigmatism.
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