Short-Term Impact of Different Corneal Incision Positions on Postoperative Astigmatism and Visual Quality After SMILE Surgery.

INTRODUCTION: This study aimed to evaluate the short-term impact of different incision positions on astigmatism and visual quality after small incision lenticule extraction (SMILE) surgery. METHODS: This prospective study enrolled patients who decided to have SMILE to correct myopia. Patients were randomly allocated into three groups of different incision positions (group A, B, and C with incision position at 90°, 120°, and 150° respectively). Preoperative and postoperative visual acuity, spherical equivalent, and high-order aberrations (HOAs) were measured and compared among groups. Astigmatism was analyzed with the ASSORT Group Analysis Calculator based on the Alpins method. RESULTS: A total of 148 eyes were included for analysis (48 eyes in group A, 50 eyes in group B, and 50 eyes in group C). At 1 month postoperatively, the mean uncorrected distance visual acuity (UDVA) logMAR in group A, B, and C was - 0.03, - 0.03, and - 0.04, respectively. The mean corrected distance visual acuity (CDVA) logMAR in group A, B, and C was - 0.03, - 0.04, and - 0.04, respectively (P > 0.05). The mean postoperative spherical equivalent (SE) values were - 0.01 ± 0.38, - 0.07 ± 0.39, and - 0.16 ± 0.49 (D) in group A, B, and C, respectively (P > 0.05). There was no statistically significant difference in preoperative and postoperative magnitude of astigmatism among different groups (P > 0.05). Significant differences were found in the distribution of astigmatism axis among the three groups at 1 day (P = 0.02) and 1 week (P = 0.02) postoperatively. However, such differences were no longer significant at 1 month after surgery (P > 0.05). No significant differences were found in HOAs among different groups 1 month after surgery (P > 0.05). CONCLUSION: Different incision positions have no effect on postoperative astigmatism and visual quality 1 month after SMILE surgery, though differences were found in the distribution of the astigmatism axis within 1 week after the surgery.