During “normal” LASIK, an IntraLase machine is used to create a flap, following which an excimer laser is used to reshape the cornea.
Advanced Surface Ablation (ASA), Photorefractive keratectomy (PRK) and LASEK is a flapless LASIK method. Instead of creating a flap, the surgeon removes the epithelium of the cornea. Aside from that, the remaining treatment steps are the same as those in normal LASIK.