Risk factors for intraoperative epithelial defect in laser in-situ keratomileusis

PURPOSE: To report intraoperative epithelial defects (IED) in eyes undergoing laser in-situ keratomileusis (LASIK). DESIGN: Consecutive interventional case series. METHODS: Retrospective review of 247 eyes (133 patients) that underwent primary LASIK by a single surgeon at an academic institution using the Hansatome microkeratome. Patient characteristics and variations in preoperative and operative technique were analyzed. The main outcome measure was occurrence of IED (defined as loose epithelium that is > 1 mm or cannot be stably repositioned or absent epithelium). Multivariate logistic regression was performed. RESULTS: Intraoperative epithelial defects occurred in 24 (9.7%) of 247 eyes. Intraoperative epithelial defects significantly increased with older age (odds ratio [OR] 2.39/decade; 95% confidence interval [CI] 1.46-3.92), thicker preoperative corneal thickness (OR 2.30/50 μm; 95% CI 1.24-4.28), and maintenance of suction ring vacuum during the reverse pass of the microkeratome (OR 1.76; 95% CI 1.01-3.06). The preoperative and intraoperative eye-drop regimen (anesthetic, mydriatics, lubricants, and intraoperative tonometry) had a significant effect on IED risk (OR, 0.163 best vs worst regimen; 95% CI, 0.033-0.792). In patients undergoing bilateral LASIK, the incidence of IED is much higher in the second eye if the first eye developed an IED (57% vs 1%). CONCLUSIONS: Modifying the eyedrop regimen was the more effective technical approach to decrease the risk of IED. Age and corneal thickness are valuable patient characteristics for preoperative risk assessment. Intraoperative epithelial defects in the first eye is highly predictive of IED in the second eye of the same patient.