Comparison of in vivo confocal microscopic findings between epi-LASIK procedures with different management of the epithelial flaps.

Purpose: To use in vivo confocal microscopy to compare the wound-healing process in epikeratome laser-assisted in situ keratomileusis (epi-LASIK) with different management of the epithelial flaps.
Methods: This prospective study comprised 46 eyes in the on-flap group and 47 eyes in the off-flap group. Epithelial flaps were repositioned or removed in the on- and off-flap eyes, respectively. In vivo confocal microscopy was performed before surgery and at 1 and 2 weeks and 1, 3, and 6 months after surgery. Corneal epithelial thickness, basal/apical surface epithelial morphology, and stromal reactions were analyzed.
Results: Complete epithelialization by slit lamp biomicroscopy was faster for mitomycin C (MMC)-treated off-flap (4.27 ± 0.70 days) than on-flap (5.84 ± 0.08 days) eyes (P = 0.01). The percentage of eyes recovering to preoperative basal epithelial cell confocal morphology in the on- and off-flap groups was 87.5% and 92.3% for MMC-treated eyes and 86.3% and 90.5% in eyes without MMC treatment at 1 month after surgery. Of the studied eyes, with or without MMC, 50% and 100% returned to their preoperative apical epithelial morphology by 3 months in the on-flap and off-flap groups, respectively. Regression analysis revealed that the repositioned flap resulted in significant delay of epithelialization and apical-basal epithelial recovery (P < 0.01). Stromal reaction did not differ significantly at any of the time points. Corneal epithelial thickness was significantly thicker in the on-flap eyes (54.2 ± 4.5 μm) than in the off-flap eyes (26.7 ± 5.8 μm) at 1 month after surgery (P < 0.01).
Conclusions: On- and off-flap epi-LASIK showed comparable clinical outcomes after surgery. Off-flap epi-LASIK had more rapid re-epithelialization and normalization of epithelial morphology than did on-flap epi-LASIK, when observed by in vivo confocal microscopy. (ClinicalTrials.gov number, NCT00491439.).