LASIK or Lasik (laser-assisted in situ keratomileuses) is a type of refractive surgery for correcting myopia, hyperopia, and astigmatism. LASIK is performed by ophthalmologists using a laser. The procedure is generally preferred to photorefractive keratectomy, PRK, (also called ASA, Advanced Surface Ablation) because it requires less time for the patient's recovery, and the patient feels less pain overall. However, there are special instances where a PRK/ASA procedure is medically justified as being a better alternative to LASIK.

Many patients choose LASIK as an alternative to wearing corrective eyeglasses or contact lenses.