It is the most recent advance in the field of refractive surgery. LASIK is used to reshape the cornea, which is the most powerful lens in the eye. It uses an excimer laser (a cool beam of light) to reshape the cornea and improve vision. The superficial layer of the cornea is raised as a flap and laser is applied to the underlying bed (hence also called as flap and zap). The flap is then replaced. LASIK stands for Laser Assisted In Situ Keratomileusis.