Both LASIK and ASA utilize an excimer laser to reshape the cornea. The laser is so precise that it takes several pulses of light to remove a single cell. In ASA, the laser is used on the surface of the eye, which requires a slightly longer healing time, with most patients able to drive in 24-48 hours. LASIK involves creating a thin flap of tissue, retracting the flap, and applying the laser underneath the flap. The flap is then replaced, and it adheres very quickly on its own. Discomfort with both procedures is typically mild.