A controlled vacuum allows the microkeratome to be positioned precisely over the eyeball. In just a few seconds, the microkeratome opens the surface of the cornea in a fully-automated, computer-controlled process (according to predetermined parameters). The resulting circular flap is not completely separated from the cornea, but remains firmly attached by a "hinge" of residual tissue. The flap is folded back to expose the surgical "field" so that the laser can then do its work. The precision of the resection and the corneal tissue removed by the laser produce an exact correction of the patient's eyesight. The flap is then folded back in place. The system can be used to correct farsightedness, nearsightedness and astigmatism.