Complications can involve the epithelium, or the tissue that covers the top of the cornea. Epithelial complication rates vary, but generally they are considered to occur in about 2 out of 100 patients. These complications typically do not affect the final outcome of your vision in any way, but they may increase the likelihood of a delayed complication known as epithelial ingrowth.
Epithelial ingrowth is when healing tissue develops under the flap along or in the areas that are cut. If this ingrowth occurs on the outer edges or does not cause problems, it is left alone. If vision is affected, however, in most cases it can be corrected surgically by removing the epithelial ingrowth.