Long-term Observation of Decentration in High and Low-to-moderate Myopia Following Small Incision Lenticule Extraction (SMILE).
PURPOSE To investigate the long-term decentration changes and associated factors after SMILE surgery for high and low-to-moderate myopia. METHODS 47 eyes of 30 patients undergoing SMILE surgery at the Eye & ENT Hospital of Fudan University were included in this prospective study (age at surgery: 28.23 ± 7.38 years old, male:female = 13:17). 20 eyes of 15 patients were divided into low-to-moderate myopia (LMM) group, and 27 eyes of 20 patients to high myopia (HM) group by preoperative refraction. Main outcome measures included visual acuity, preoperative refraction, intraocular pressure, axial length, optical zone diameter, decentration, and ablation depth. Follow-up time was 11.50 ± 1.52 years (10 to 13 years). RESULTS All surgeries were successful without complications. The safety index was 1.18 ± 0.17 in HM group and 1.19 ± 0.17 in LMM group. The decentration was 0.38 ± 0.20 mm in HM group and 0.48 ± 0.19 mm in LMM group, with no statistically significant difference between groups (p = 0.130). In LMM group, decentration was negatively correlated with spherical refraction (r = -0.46, p = 0.016*) and spherical equivalent (r = -0.41, p = 0.032*), and positively correlated with corneal thickness (r = 0.50, p = 0.008*) and axial length (r = 0.51, p = 0.006*). In HM group, no significant correlation was found between decentration and evaluated factors (p > 0.05). CONCLUSION SMILE surgery demonstrates long-term safety, efficacy, and predictability. Long-term decentration after SMILE is unaffected by the degree of myopia.