Abstract
This is a prospective case-control study investigated the factors influencing ultra-early visual acuity and quality after Small Incision Lenticule Extraction (SMILE) surgery, with a specific focus on the morphology and distribution of "black clefts" observed in posterior lenticule laser scanning images. A total of 174 patients who underwent SMILE surgery were included, and their preoperative ocular clinical parameters, visual quality indicators, and posterior lenticule laser scanning images were analyzed. The morphological features of black clefts were calculated using image processing techniques. Univariate and multivariate logistic analyses were conducted to identify factors impacting ultra-early visual acuity recovery, while correlation analysis was used to explore the association between black cleft morphology and postoperative visual quality. The results showed that although patients experienced significant visual acuity improvement one day after surgery, 26% had poor early recovery. Postoperative visual quality parameters were significantly lower, while the Object Scatter Index (OSI) was higher compared to preoperative values. Patients with poor visual recovery had a higher number of irregular black clefts in their laser scanning images. Logistic regression analysis revealed that intraoperative morphological parameters of black clefts were independent factors influencing early postoperative visual acuity recovery. Additionally, correlation analysis demonstrated a negative correlation between black cleft morphology and postoperative visual quality parameters, and a positive correlation with OSI. In conclusion, the morphology and distribution of black clefts during SMILE surgery significantly affect ultra-early postoperative visual acuity and quality, with increased variability in black cleft area leading to higher OSI, thereby impacting visual quality recovery.