Comparison of the Functional Optical Zone in Eyes With High Myopia With High Astigmatism After SMILE and FS-LASIK

PURPOSE: To compare the functional optical zone (FOZ) in eyes with high myopia with high astigmatism after small incision lenticule extraction (SMILE) and femtosecond laser-assisted laser in situ keratomileusis (FS-LASIK).METHODS: In total, 45 eyes of 45 patients with high myopia with astigmatism greater than 2.00 diopters (D) who under-went SMILE or FS-LASIK were enrolled. The FOZ, optical zone decentration, and corneal aberrations were analyzed using Scheimpflug imaging. These values were then compared be-tween the two groups 6 months postoperatively.RESULTS: No postoperative complications were observed during follow-up. The mean FOZ diameter was 5.03 +/- 0.31 mm for the FS-LASIK group and 5.24 +/- 0.27 mm for the SMILE group (P = .007), corresponding to reductions of 1.18 +/- 0.23 and 1.01 +/- 0.21 mm, respectively, compared with the programmed optical zone (POZ) (P = .013). A significant dif-ference was noted in the FOZ on the short axis between the two groups (P = .002), whereas no significant difference was observed on the long axis (P = .088). The FOZ area in the FS-LASIK and SMILE groups was 65.39 +/- 6.14% and 70.09 +/- 5.46% of the POZ area, respectively (P = .010). There was no significant difference in decentration between the two groups (0.29 +/- 0.13 mm for the FS-LASIK group vs 0.30 +/- 0.13 mm for the SMILE group, P = .798). A significant increase in spherical aberration was observed in the FS-LASIK group (P < .001). However, the induction of vertical coma was higher in the SMILE group than in the FS-LASIK group (P = .002).CONCLUSIONS: Eyes with high myopia with high astigmatism following SMILE achieved a larger FOZ and less spherical ab-erration but a larger vertical coma introduction than follow-ing FS-LASIK.