Epithelial ingrowth is a complication of LASIK surgery wherein cells from the thin surface layer of the cornea (the epithelium) start growing underneath the corneal flap that's produced in the procedure. It may take several weeks for this process to become evident after surgery.
The incidence of epithelial ingrowth after LASIK has been reported to be as low as 0.2% and as high as 15%. In one study of over 1,300 LASIK procedures, epithelial ingrowth occurred in 0.2% of eyes undergoing a primary LASIK procedure, and in 6% of eyes undergoing a LASIK enhancement. Incidence of epithelial ingrowth in this study was essentially the same regardless whether the corneal flap was created with a microkeratome or a femtosecond laser.
Most cases of epithelial ingrowth are self-limiting, don't cause discomfort or vision problems, and do not require treatment. However, in some cases, the ingrowth causes problems and must be removed. This requires the refractive surgeon to lift the corneal flap. After the sheet of epithelial cells is removed, the flap is replaced. The surgeon may apply a bandage contact lens or use a surgical glue to help the flap seal and decrease the risk for a recurrence of the epithelial ingrowth.
Some research suggests your risk of epithelial ingrowth is greater if you are farsighted prior to surgery or if you are over age 40.