Effects of SMILE and FS-LASIK on choroidal thickness and blood flow density in patients with myopia

Abstract

Abstract Purpose: This study aimed to evaluate the changes in choroidal thickness and blood flow density after small-incision lenticule extraction (SMILE) and femtosecond laser-assisted in-situ keratomileusis (FS-LASIK) using an optical coherence tomography system (OCT). Methods: In this study, patients who underwent myopia surgery between May 2021, and October 2022, were randomly selected. The patients were divided into two groups on the basis of surgical method: SMILE group and FS-LASIK group. The diopter, axial length of the eyeball, choroidal thickness, and blood flow density of the patients were tracked and measured before the surgery, and at 1 week, 1 month, and 3 months after the surgery. Results: A total of 56 patients (112 eyes) were included in the study, with 35 individuals (70 eyes) in the SMILE group and 21 individuals (42 eyes) in the FS-LASIK group. The postoperative diopter of both groups showed a significant improvement (P < 0.05), and the axial length of the eyes was shorter than the baseline level (P < 0.05). After the operation, the choroidal thickness of the two groups showed a trend of first increasing and then decreasing at multiple measurement sites, and only few sites were basically stable after the thickness increased. No significant change was observed in the choroidal blood flow density between the two groups after the operation. Conclusion: In this study, the axial length of the eye shortened after SMILE and FS-LASIK, the thickness of the choroid at only few sites increased and remained stable, and the choroidal blood flow density did not change significantly. The choroid was less affected after corneal refractive surgery.