Epithelial ingrowth in the interface under a LASIK flap. A, Peripheral ingrowth of 1–2 mm (arrows) is common and inconsequential and does not require intervention unless it induces melting of the overlying flap. B, Central nests of epithelial cells (arrow) disrupt the patient’s vision by elevating and distorting the flap. The flap must be lifted and the epithelium debrided. C, Inspection of the midperiphery shows the track followed by the invading epithelium from the periphery toward the center (arrows).