Effect of Myopic Femtosecond Laser-Assisted LASIK on Anterior Chamber Inflammation (Flare Values) and Corneal Endothelium: A Prospective before and after Study

Purpose This study aimed to investigate whether femtosecond laser-assisted LASIK (FS-LASIK) surgery causes inflammation in the anterior chamber and to analyze its effect on endothelial cells.Methods This prospective, longitudinal study included left eyes of 30 patients (19 females) who had undergone FS-LASIK surgery due to myopia and myopic astigmatism. Endothelial cell density (ECD) and morphological measurements were performed using a specular microscopy, and laser flare photometry was used to measure the anterior chamber flare values on the day of surgery. iFS™ Advanced FS and VISX STAR S4-IR Wavescan Excimer Laser platforms were used. Flare measurements were repeated on the postoperative 1 st day and 7 th day and the 1 st and 3 rd months. The endothelial measurements were repeated in the 3 rd month.Results Preoperatively, the mean flare was 5.59 ± 1.24 photons/ms; it was 6.49 ± 2.42 on the postoperative 1 st day, 5.87 ± 2.27 on the 7 th day, 5.68 ± 1.66 on the 1 st month, and 5.35 ± 1.24 on the 3 rd month. A significant difference was observed only between the preoperative and postoperative 1 st day flare values ( p =0.047). The decrease in the ECD was clinically insignificant but statistically significant, with an average of 97.0 ± 209.9 cell count/mm 2 (3.3%, p =0.017). However, there was no significant change in the coefficient of variation ( p =0.448) and hexagonality ( p =0.096). No significant correlation was found between the increase in the flare value on the postoperative 1 st day and variables. A significant correlation was found between the decrease in ECD and the preoperative ECD ( r  = 0.356, p =0.027).Conclusion FS-LASIK caused minimal inflammation in the anterior chamber on only the 1 st postoperative day; additionally, a minimal decrease of cell count with no morphological changes were noted in the endothelial cells on postoperative 3 rd month. This trial is registered with NCT04899258 .