Three-Year Results of Small Incision Lenticule Extraction for High Myopia: Refractive Outcomes and Aberrations

PURPOSE: To assess the 3-year refractive and visual outcomes after small incision lenticule extraction (SMILE) in patients with high myopia and to evaluate the optical changes from 3 months to 3 years after surgery. METHODS: A total of 87 eyes (87 patients) undergoing SMILE for high myopia were included. Preoperative and 3-month and 3-year postoperative follow-up examinations included manifest refraction and uncorrected and corrected distance visual acuities. Pentacam HR (Oculus Optikgeräte, Wetzlar, Germany) was used to evaluate the total corneal refractive power and the root mean square of spherical aberration, coma, and total higher-order aberrations. The paired t test and Wilcoxon signed rank test were used. RESULTS: The preoperative spherical equivalent averaged -7.30 ± 1.40 diopters (D); no significant changes occurred between 3 months and 3 years after surgery (-0.30 ± 0.50 vs -0.40 ± 0.60 D, P = .071). Uncorrected distance visual acuity was stable from 3 months to 3 years after SMILE (0.04 ± 0.17 vs 0.03 ± 0.19 logMAR; P = .28), whereas corrected distance visual acuity improved from -0.05 ± 0.15 to -0.08 ± 0.11 logMAR (P < .001). At 3 months, 82% and 93% of eyes were within ± 0.50 and ± 1.00 D, respectively. At 3 years, 78% and 90% were within ± 1.00 D of the attempted refraction, respectively. Spherical and higher-order aberrations significantly decreased from 3 months to 3 years, whereas coma remained stable. A significant regression of 0.36 ± 0.29 D was seen in total corneal refractive power (P < .001). CONCLUSIONS: The refractive and visual outcomes seemed stable years after SMILE. A minor myopic regression was observed in total corneal refractive power but not in subjective refraction. There seems to be a significant long-term improvement in higher-order aberrations after surgery.