Longitudinal and Regional Non-uniform Remodeling of Corneal Epithelium After Topography-Guided FS-LASIK

PURPOSE: To observe the epithelial remodeling over a 9-mm diameter cornea induced by topography-guided femtosecond laser–assisted in situ keratomileusis (FS-LASIK) for myopia correction using spectral-domain optical coherence tomography (SD-OCT). METHODS: Forty-three eyes of 22 patients who underwent topography-guided FS-LASIK for myopic correction were included. The “Pachymetrywide” scan pattern was used to generate the epithelial thickness map using SD-OCT preoperatively and 1, 3, and 6 months postoperatively. Epithelial thickness was compared and analyzed by section and zone. RESULTS: Compared to the preoperative values, the change in the average epithelial thickness in the central, paracentral, and mid-peripheral zones was 2.09, 4.53, and −0.87 µm at 1 month; 3.00, 4.61, and −0.97 µm at 3 months; and 3.28, 4.55, and −0.81 µm at 6 months postoperatively, respectively. From 1 to 3 months postoperatively, the central epithelial thickness changed significantly ( P = .021), whereas the epithelial thickness in the paracentral ( P = .973) and mid-peripheral ( P = .996) zones stabilized. No significant epithelial thickness change was observed in the zones between 3 and 6 months postoperatively (all P > .05). The epithelial thickness in the paracentral inferotemporal section increased by 12.7% at 6 months after surgery. The central epithelial hyperplasia showed no correlation with the change in postoperative manifest refraction spherical equivalent ( P = .313). CONCLUSIONS: After topography-guided FS-LASIK, the 9-mm diameter epithelial thickness showed a longitudinal and regional non-uniform redistribution. Central epithelial remodeling stabilized more slowly. The greatest increase in epithelial thickness was observed in the paracentral inferotemporal section. This epithelial remodeling did not cause refractive regression. [ J Refract Surg . 2019;35(2):88–95.]