The technique involves the removal of superficial corneal tissue under a protective corneal flap. The removal of this tissue alters the curvature of the cornea, allowing better focusing of light on to the retina.Pre-operative evaluation is vital as it is necessary to assess how much of the stromal bed should be removed. Normal patients have a cornea that is usually 550-600 microns thick. At least 250 microns of the stromal bed should remain during LASIK surgery to reduce the risk of corneal instability caused by excessive thinning of the stromal bed.
