Visual and Refractive Outcomes of Photorefractive Keratectomy and Small Incision Lenticule Extraction (SMILE) for Myopia.

Abstract

To compare the refractive outcomes of small incision lenticule extraction (SMILE) with photorefractive keratectomy (PRK) using an aberration-free ablation profile. One eye of patients diagnosed as having myopia for bilateral refractive correction was randomly allocated to either PRK or SMILE. The primary outcome measures included refractive efficacy, predictability, safety, stability, corneal aberrations, and adverse events. Patients were followed up for 1 year postoperatively; postoperative uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), manifest refraction, and corneal aberrations were recorded and compared with preoperative data. Thirty-nine patients in the PRK group and 35 patients in the SMILE group completed the study. The mean preoperative spherical equivalent refractions were -3.27 ± 0.62 diopters (D) for the PRK group and -3.56 ± 1.12 D for the SMILE group. The average postoperative spherical equivalent refractions were -0.26 ± 0.29 and -0.43 ± 0.38 D for the PRK and SMILE groups, respectively (P = .06). Total higher order aberrations in the 6-mm central corneal zone were significantly higher in the SMILE group (0.21 ± 0.10 µm) than in the PRK group (0.09 ± 0.03 µm) (P = .01) 12 months postoperatively. However, no statistically significant differences were found among spherical, trefoil, and coma aberrations between the groups. The refractive results of PRK with aberration-free aspheric ablation are similar to those of SMILE in eyes with low myopia. The induction of coma, spherical, and trefoil aberrations did not statistically differ after both surgeries, but the total higher order aberrations after SMILE were significantly higher than PRK with aberration-free aspheric ablation. [J Refract Surg. 2016;32(9):604-610.].