Comparison of efficacy and visual outcomes after SMILE and FS-LASIK for the correction of high myopia with the sum of myopia and astigmatism from -10.00 to -14.00 dioptres.

Purpose: To compare the efficacy and visual outcomes after femtosecond laser small incision lenticule extraction (SMILE) and femtosecond laser-assisted laser in situ keratomileusis (FS-LASIK) in correcting high myopia.

Methods: This prospective, randomized study included patients who underwent SMILE or FS-LASIK for the correction of high myopia [the sum of spherical and cylindrical error from -10.00 to -14.00 dioptres (D)]. Preoperative, 1-month (P1m), 3-months (P3m) and 6-months (P6m) postoperative outcomes were analysed and compared between the two procedures.

Results: Ninety-six right eyes of 96 patients (SMILE: n = 51, FS-LASIK: n = 45) were included. Both the (Attempted - achieved) sphere and the (attempted - achieved) spherical equivalent (SEQ) were greater in the FS-LASIK group at all three postoperative time-points (p < 0.001). The postoperative vector means of astigmatism were smaller in the SMILE group than in the FS-LASIK group. The differences between the optical zone of tissue removal (ROZ) during surgery and the postoperative functional optical zone (FOZ; ROZ-FOZ) were smaller in the SMILE group than in the FS-LASIK group. No significant difference was found between the two procedures in the delta-root mean square (RMS) of aberrations, except for delta-spherical aberration (SA) at P3m.

Conclusions: Both SMILE and FS-LASIK are effective in correcting high myopia. SMILE resulted in less under-correction, less regression, a smaller decrease in the FOZ and a smaller increase in SA when compared to FS-LASIK, resulting in better visual outcomes with SMILE.