One-year outcomes of small-incision lenticule extraction (SMILE): Mild to moderate myopia vs. high myopia

Background: The purpose of this study was to compare the refractive outcomes of small incision lenticule extraction (SMILE) in high-myopic patients with those of mild- to moderate-myopic patients. Methods: This study included 183 eyes of 92 myopic patients treated with SMILE using a VisuMax 500-kHz femtosecond laser. Treated eyes were divided into two groups, according to the preoperative spherical equivalent (SE): mild to moderate myopia (A group, <-6.0 D) and high myopia (B group, =∈-∈6.0 D). Follow-up visits were at 1 day, 1 week, and 1, 3, 6, and 12 months. The outcome measures included uncorrected distance visual acuity (UDVA), best-corrected distance visual acuity (BDVA), postoperative SE, efficacy index, safety index, and predictability. Results: Preoperative SE was -5.05∈±∈0.71 D in the A group and -7.67∈±∈1.01 D in the B group. No differences were observed between -0.13∈±∈0.38 D in the A group and -0.24∈±∈0.35 D in the B group 12 months postoperatively (p∈=∈0.18). At 12 months postoperatively, 93.1 % and 76.8 % had an UDVA of 20/20 or better in the A and B groups, respectively. In the A group, 87.9 % and 96.6 % were within ±0.5 D and ±1.0 D, respectively, of the intended correction; in the B group, 88.0 % and 97.6 % were within ±0.5 D and ±1.0 D, respectively. The efficacy index was 1.04∈±∈0.19 in the A group and 0.99∈±∈0.19 in the B group. The safety index was 1.27∈±∈0.17 for the A group and 1.24∈±∈0.17 for the B group. The efficacy and safety index were not significantly different between the two groups 12 months postoperatively (p∈=∈0.141 and p∈=∈0.307, respectively). Conclusions: This study showed that SMILE is effective and safe for correcting high myopia, as well as mild to moderate myopia.