Abstract: Objective To investigate the visual acuity improvement and related factors in myopic patients after small incision lenticule extraction(SMILE), in order to provide clinical data for standardization of SMILE surgery. Methods This retrospective clinical study included a total of 64 myopic patients(128 eyes)between January 2016 and August 2016. All patients underwent standard SMILE surgery performed by a single experienced surgeon. Visual acuity was assessed 1 day and 1 week after surgery. Correlations among postoperative uncorrected visual acuity(UCVA)and preoperative factors such as age, gender, preoperative equivalent sphere(SE), keratometry, central corneal thickness(CCT), as well as postoperative factors such as residual stromal bed thickness(RST)and ablation depth/corneal thickness ratio(AD/CT)were statistically analyzed. Results On postoperative day 1, 30.4% of eyes achieved a UCVA of 0.8 or better and 10.2% eyes achieved a UCVA of 1.0 or better. Additionally, 5.5% of the eyes achieved preoperative best corrected visual acuity(BCVA). At 1 week postoperatively, 90.6% of the eyes achieved a UCVA of 0.8 or better and 64.1% of the eyes achieved a UCVA of 1.0 or better. Additionally, 33.6% of the eyes achieved preoperative BCVA. No significant correlations were observed among the preoperative and postoperative visual acuity and age, gender, keratometry, CCT, SE, RST, and AD/CT. Conclusion Recovery of early visual acuity may be correlated with corneal wound healing and inflammatory responses, and changes in the corneal microstructure may be another factor responsible for slower visual recovery following SMILE.

Key words: Small incision lenticule extraction, Femtosecond laser, Myopia