Fellow Eye Comparison of Nerve Fiber Regeneration After SMILE and Femtosecond Laser-assisted LASIK: A Confocal Microscopy Study.

Abstract To compare postoperative corneal nerve fiber regeneration after small incision lenticule extraction (SMILE) and femtosecond laser-assisted LASIK (FS-LASIK). The medical records of patients who underwent SMILE were retrospectively reviewed. Patients with SMILE in one eye (the SMILE group) and FS-LASIK in the fellow eye (the FS-LASIK group) and who had undergone a confocal microscopy study were retrospectively identified. Subbasal nerve fiber density was measured and compared between the groups preoperatively and at 1 week and 1, 3, and 6 months postoperatively. Thirty eyes of 15 patients were included in the study. Preoperative characteristics of the eyes were similar between the groups. However, there was a statistically significant difference in subbasal nerve fiber density between the groups at 1 month (SMILE group: 1,505 ± 627 µm/mm(2) [range: 625 to 2,540 µm/mm(2)], FS-LASIK group: 1,107 ± 509 µm/mm(2) [range: 595 to 2,313 µm/mm(2)], P = .003) and 3 months (SMILE group: 1,534 ± 503 µm/mm(2) [range: 650 to 2,255 µm/mm(2)], FS-LASIK group: 1,194 ± 485 µm/mm(2) [range: 530 to 1,695 µm/mm(2)], P = .004) postoperatively. No statistically significant difference was detected at 1 week and 6 months postoperatively. Eyes treated with SMILE have a higher density of subbasal nerve fibers than eyes treated with FS-LASIK in the early postoperative period (1 week to 3 months) but the two procedures are equivalent by 6 months postoperatively.