Comparison of outcome between small incision lenticule extraction and FS-LASIK in eyes having refractive error greater than negative 10 diopters.

PURPOSE To compare small incision lenticule extraction (SMILE) and femtosecond laser-assisted laser in situ keratomileusis (FS-LASIK) in terms of safety, refractive outcomes, visual quality, and biomechanical responses in correcting myopia with maximum myopic meridian exceeding 10 diopters (D). SETTING Zhongshan Ophthalmic Center, Sun Yat-sen University. DESIGN Prospective, randomized, comparative study. METHODS The study comprised 60 eyes (60 patients) with a maximum myopic meridian exceeding 10 D; 30 eyes were corrected using SMILE and 30 eyes were corrected using FS-LASIK. Patients received preoperative and 6-month postoperative examinations, including refractive outcomes, corneal curve, contrast sensitivity, ocular aberrometry, and corneal biomechanical responses. RESULTS At 6 months postoperatively, the uncorrected distance visual acuity was -0.01 ± 0.06 and -0.05 ± 0.10 in the SMILE and LASIK eyes, respectively (P = .08). The corrected distance visual acuity was -0.07 ± 0.07 and -0.08 ± 0.08 (P = .624), respectively. The postoperative spherical equivalent (SE) was -0.20 ± 0.25 D and -0.03 ± 0.20 D, respectively (P = .008). The posterior corneal curvature was unchanged after SMILE and FS-LASIK (P > .05). The measured corneal thickness was reduced by 137.40 ± 15.01 μm and 155.06 ± 17.43 μm (P < .001). The change in the SE was -0.01 ± 0.26 and -0.13 ± 0.30 from 1 week (P = .103). Only the peak distance (the distance between the highest points of the nondeformed corneal parts) differed between the groups (1.06 ± 1.44 mm vs -0.26 ± 1.16 mm, P = .007). In the SMILE patients, changes in higher-order aberration (P = .018) and spherical aberration (P = .011) were smaller than in LASIK patients. CONCLUSIONS Compared with LASIK, SMILE might offer superior safety and objective visual quality, comparable stability and efficacy, and a little inferior predictability in correcting maximum myopic meridian exceeding 10 D.