ASA is another type of refractive eye surgery for correcting myopia (nearsightedness), hyperopia (farsightedness), and astigmatism. This technique is employed when the corneal tissue thickness is inadequate for the LASIK technique to be performed. ASA was developed from PRK (Photo-Refractive Keratectomy) with improvements in application of the laser and treatment protocols.
ASA permanently changes the shape of the cornea using an excimer laser to remove a small amount of tissue from the cornea, the clear tissue at the front of the eye, after removal of its epithelium, the outer layer of the cornea. The eye heals well to provide the same results as the LASIK approach, but the visual recovery takes several days longer.