Comparison of postoperative corneal optical density changes and influencing factors between SMILE and FS-LASIK for...

To compare postoperative changes in corneal optical density (COD) and their influencing factors between small incision lenticule extraction (SMILE) and femtosecond laser-assisted in situ keratomileusis (FS-LASIK) in patients with high myopia. A retrospective analysis was conducted on patients with high myopia who underwent SMILE (n = 132 eyes) or FS-LASIK (n = 147 eyes). COD measurements were obtained using a Scheimpflug camera at baseline and at 1-day, 1-week, 1-month, 3-months, and 6-months postoperatively. COD was evaluated in the 0 to 2, 2 to 6, 6 to 10, and 10 to 12 mm regions. Changes in COD across different time points and regions were compared between the 2 groups. Both groups demonstrated a decreasing trend in average COD at 6-months postoperatively. Changes in COD were influenced by the surgical type, corneal region, and time point (all P < .05). In the 0 to 2 and 2 to 6 mm regions, COD at 1-week and 1-month postoperatively was higher in the SMILE group compared to the FS-LASIK group (all P < .05). In the 0 to 2 mm region, baseline COD and cap/flap thickness were identified as factors influencing COD changes at 1-week postoperatively, while baseline COD was the sole factor at 1-month postoperatively (all P < .05). In the 2 to 6 mm region, baseline COD was a factor influencing COD changes at 1-week postoperatively in the SMILE group, whereas flap thickness was the main factor in the FS-LASIK group. At 1-month postoperatively, baseline COD was the only influencing factor in both groups (all P < .05). Postoperative COD changes were influenced by surgical type, corneal region, and time point. At 1-week and 1-month postoperatively, COD in the 0 to 6 mm region was higher in the SMILE group compared to the FS-LASIK group, potentially due to differences in baseline COD and cap/flap thickness between the 2 procedures.