LAUSR

AIM To compare the subjective and objective visual quality between small incision lenticule extraction (SMILE) and transepithelial photorefractive keratectomy (tPRK) in patients with low and moderate myopia. METHODS Patients undertaking SMILE or tPRK for the correction of low and moderate myopia were consecutively recruited in this prospective cohort study with a 3-month follow-up period. Objective evaluation [visual acuity test, manifest refraction, wavefront aberrations, the total cut-off value of the total modulation transfer function (MTFcut-off), and Strehl ratio (SR)] and subjective evaluation of visual quality (quality-of-life questionnaire) were conducted before surgery and at days 1, 7, 30, and 90 after surgery. RESULTS A total of 47 patients (94 eyes) with SMILE and 22 patients (22 eyes) with tPRK were enrolled. The uncorrected visual acuity (UCVA) was better in SMILE patients on day 7 after surgery (1.13±0.13 vs 0.99±0.17, t=4.85, P<0.001) but was comparable at days 30 and 90. At day 90, the SMILE group had a lower spherical equivalent (SE) than the tPRK group (0.04±0.31 vs 0.19±0.43, t=2.08, P=0.042). Total higher order aberrations (HOAs) were induced in both surgical types, which were more evident in the tPRK group with 3-mm pupil diameter (0.16±0.07 vs 0.11±0.05, t=4.27, P<0.001) and 5-mm pupil diameter (0.39±0.17 vs 0.36±0.11, t=2.33, P=0.022). The MTFcut-off and SR showed a trend of improvement in both SMILE and tPRK patients but were statistically better in the SMILE group with both pupil diameters. There was a significant improvement of contrast sensitivity (CS) over baseline levels at the spatial frequency of 18 cycles/degree (c/d) in the SMILE group (F=2.72, P=0.033) and at 3 c/d (F=3.03, P=0.031), 12 c/d (F=3.72, P=0.013), and 18 c/d (F=4.62, P=0.004) in the tPRK group. The subjective quality of life questionnaire showed a steady improvement in the SMILE group (F=8.31, P<0.001) but not the tPRK group. CONCLUSION SMILE and tPRK are both safe and effective ways to correct low and moderate myopia. A generally better and quicker recovery of visual quality favors the application of SMILE in qualified patients.