Changes in Binocular Visual Function after SMILE

Objective: To investigate the effect of small incision lenticule extraction (SMILE) on binocular visual function and its clinical significance. Methods: In this prospective clinical study, 58 myopia patients (116 eyes) who completed the SMILE surgery at the Xiangya Hospital of Central South University from March 2016 to October 2017 were selected. According to the degree of spherical equivalent (SE), patients were divided into a high myopia group (<-6.00 D) (40 eyes) and a mild-moderate myopia group (≥-6.00 D) (76 eyes). Based on the dominant eye, participants were divided into a dominant eye group (58 eyes) and a nondominant eye group (58 eyes). For all patients, accommodative and convergence function were measured before surgery and 1 week and 1 and 3 months after surgery. Repeated measures analysis of variance and independent t-tests were used to analyze and compare the data from the two groups. Results: ①The SEs of the two groups after 1 week, 1 month, and 3 months were lower than those before surgery (P<0.05). In the mild-moderate myopia group, the dominant eye amplitude of the postoperative accommodation and the positive relative accommodation were both larger than those before surgery (P<0.05). Binocular accommodative facility increased 1 month and 3 months after surgery (P<0.05). There were no statistically significant differences in similar indicators between the high myopia group at each time point before or after surgery. There was no significant difference between the mild-moderate myopia group and the high myopia group in the amplitude of accommodation of the dominant and non-dominant eyes at each time point before and after surgery. ②There was no statistically significant difference between the preoperative mild-moderate myopia group and the high myopia group in near and distance phoria, NRV/PRV, and AC/A. The postoperative near-points in the low-moderate myopia group and the high myopia group increased compared with preoperative measurements (P<0.05). Conclusions: SMILE surgery has a positive effect on accommodative and convergence function in patients with mild-moderate myopia. For patients with high myopia, changes in postoperative binocular visual function are not obvious. Key words: small incision lenticule extraction; myopia; accommodation; vergence; binocular visual function symptom