Dec. 12, 2015. LASIK (laser-assisted in situ keratomileusis) is an outpatient refractive surgery procedure used to treat nearsightedness, farsightedness and astigmatism. A laser is used to reshape the cornea — the clear, round dome at the front of the eye — to improve the way the eye focuses light rays onto the retina at the back of the eye. With LASIK, an ophthalmologist creates a thin flap in the cornea using either a blade or a laser.