Removal of epithelial downgrowth after LASIK
Ingrowth of epithelium into the corneal flap interface is a relatively uncommon complication of LASIK. The incidence of visually significant epithelial ingrowth is about 1% in primary cases and 2% on enhancement cases in microkeratome-assisted flap creation. The incidence may be less with femtosecond-assisted flap creation.Ingrowth of these cells into the corneal stromal interface is usually asymptomatic, however, these cells may lead to decreased vision due to irregular corneal astigmatism, direct intrusion of cells into the visual axis, or lead to melting of the overlying flap. Treatment is generally needed in instances where there is decreased vision or threat for a flap melt.
Several preoperative and intraoperative risk factors have been identified. Preoperative risk factors include any factor that contributes to an epithelial defect; such as epithelial basement membrane dystrophy, history of recurrent erosions, increased patient age, diabetes mellitus, and epithelial ingrowth in the contralateral eye. Operative risk factors include intraoperative epithelial defect, postoperative inflammation (lamellar keratitis), flap relift, enhancement procedure, flap edema from any cause, flap misalignment or shift, ablation extending past the flap diameter, irregular flaps, buttonholes, free cap, LASIK in prior corneal transplantation or radial keratotomy.
LASIK patients should be evaluated for risk factors which may lead to an intraoperative epithelial defect. These include recurrent corneal erosions, epithelial basement membrane dystrophy, or chronic eye rubbing. The surgeon should practice excellent surgical technique with minimal epithelial manipulation and accurate flap apposition. Excessive topical anesthetic use, interface irrigation, or surface drying may contribute to epithelial defect formation. A bandage contact lens should be strongly considered in the event of an intraoperative epithelial defect. The incidence of epithelial ingrowth is lower when the flap is created using a femtosecond laser as compared to microkeratome.
When performing an enhancement procedure, attention should be given to removing the peripheral epithelium from the flap interface and obtaining excellent flap apposition when replacing the flap.