Comparison of Corneal Epithelial Remodeling Over 2 Years in LASIK Versus SMILE: A Contralateral Eye Study

Purpose: To evaluate 3-dimensional epithelial remodeling in patients undergoing myopic laser in situ keratomileusis (LASIK) versus small incision lenticule extraction (SMILE). Methods: In a prospective randomized contralateral eye study of LASIK versus SMILE procedures, 21 consecutive patients (42 eyes) were evaluated with corneal epithelial mapping by anterior segment optical coherence tomography for up to 2 years. Results: In the LASIK group, central epithelial thickness increased from 52.38 ± 2.57 μm to 57.00 ± 4.23 μm and remained almost stable at this level for up to 24 months. In the SMILE eyes, it increased from 52.52 ± 3.01 μm to 57.15 ± 4.57 μm and also remained stable for up to 24 months. Both techniques created the same level of epithelial thickness increase and variation, with a significantly higher mid-peripheral epithelial thickness increase. The differences between the preoperative and postoperative changes were found statistically significant, but not different between the 2 techniques at any given time studied. Conclusions: Both LASIK and SMILE resulted in significant epithelial thickening. This response seemed to be surprisingly quite similar between the 2 different techniques. This study suggests that epithelial remodeling may correlate with relative curvature changes resulting after both techniques, rather than the obvious difference of subepithelial corneal denervation changes.