The influence of axial length on visual quality following SMILE surgery in patients with high myopia

Purpose: This retrospective study aimed to investigate the subjective and objective visual outcomes following Small Incision Lenticule Extraction (SMILE) surgery in high myopic patients with varying axial lengths (AL). Methods: The study enrolled 113 highly myopic patients (202 eyes) who underwent SMILE surgery at Shanghai's Tenth People's Hospital from July 2021 to September 2023. Patients were classified into three groups based on the axial length before surgery: Group A (AL < 26 mm, 62 eyes), Group B (26 mm <= AL < 27 mm, 88 eyes), and Group C (AL >= 27 mm, 52 eyes). Preoperative and postoperative evaluations included uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), equivalent spherical error, and ocular higher-order aberrations. Subjective visual quality was assessed using the Quality of Vision (QoV) questionnaire. Results: One year postoperatively, there were no notable differences found in safety, efficacy, or stability among the groups (P > 0.05). Postoperative spherical aberration, horizontal, and vertical coma increased compared to preoperative values and showed a positive association with axial length (P < 0.05). Horizontal and vertical trefoil remained stable at all follow-up points without any significant inter-group variances (P > 0.05). Postoperative QoV scores were obviously higher in Groups A (45.45 +/- 5.49) and B (46.34 +/- 3.25) compared to Group C (49.15 +/- 7.89). There was no correlation between QoV scores and axial length observed. The induced horizontal trefoil showed a positive correlation with changes in lens thickness (LT) one year after SMILE (r = 0.22, p = 0.03). Conclusions: SMILE surgery is a safe and effective approach for correcting high myopia, exhibiting a significant correlation observed between ocular high-order aberrations and axial length.