ObjectiveTo investigate the differences and changes in early postoperative visual quality after small incision lenticule extraction (SMILE) and smart pulse technology-assisted transepithelial photorefractive keratectomy (SPT-TransPRK).

MethodsA cohort study was performed.A total of 92 patients (92 eyes) who underwent corneal laser refractive surgery were enrolled in Dalian Third People's Hospital Affiliated to Dalian Medical University from February 2021 to May 2021.The data from the right eye were collected for analysis.The patients were divided into SMILE group (40 patients, 40 eyes) and SPT-TransPRK group (52 patients, 52 eyes). Preoperative, 1- and 3-month postoperative visual acuity were measured to calculate the effectiveness, which was defined as the ratio of postoperative uncorrected visual acuity (UCVA) to preoperative best corrected visual acuity.Refraction was measured by an AR-1 autorefractor.Corneal higher-order aberration (HOA) including total HOA, spherical aberration and coma was measured by Sirius corneal topographer.Objective scatter index (OSI), modulation transfer function cut-off frequency (MTF cut-off), Strehl ratio (SR), simulated contrast visual acuity VA100 (day), VA20 (dusk) and VA9 (night) were measured via OQAS II visual quality analysis system.This study adhered to the Declaration of Helsinki.The study protocol was approved by the Ethics Committee of the Dalian Third People's Hospital Affiliated to Dalian Medical University (No.2019-KT-010). Written informed consent was obtained from each subject.

ResultsThere was no significant difference in 3-month postoperative UCVA and effectiveness between the two groups ( Z=0.880, P=0.380; t=0.920, P=0.058). Patients in SPT-TransPRK group showed mild hyperopia 3 months after surgery.Preoperative, 1- and 3-month postoperative total corneal HOA was (0.47±0.18), (0.70±0.22) and (0.74±0.19)μm in SMILE group, and (0.40±0.14), (0.98±0.35) and (0.94±0.22)μm in SPT-TransPRK group respectively, showing statistically significant differences ( F _group=13.851, P=0.001; F _time=29.960, P<0.001). Preoperative, 1- and 3-month postoperative spherical aberration was (-0.20±0.09), (-0.44±0.14) and (-0.44±0.15)μm in SMILE group, and (-0.20±0.10), (-0.71±0.23) and (-0.75±0.20)μm in SPT-TransPRK group respectively, showing statistically significant differences ( F _group=31.037, P<0.001; F _time=48.005, P<0.001). The postoperative total corneal HOA and spherical aberration were increased in both groups compared with before surgery, with statistically significant differences (all at P<0.05). The 1- and 3-month postoperative total corneal HOA and spherical aberrations were smaller in SMILE group than in SPT-TransPRK group, and the differences were statistically significant (all at P<0.05). The 1- and 3-month postoperative coma were increased in both groups compared with before surgery, showing statistically significant differences (all at P<0.05). In SMILE group, 1-month postoperative OSI was higher and 1-month postoperative MTF cut-off, SR, and VA9 were lower than those before surgery, and 3-month postoperative OSI was higher and 3-month postoperative SR and VA9 were lower than those before surgery, showing statistically significant differences (all at P<0.05). In SPT-TransPRK group, 1-month postoperative OSI was higher and 1-month postoperative MTF cut-off, SR, VA100, VA20, and VA9 were lower than those before surgery, showing statistically significant differences (all at P<0.05). There was no significant difference in OSI, MTF cut-off, SR, VA100, VA20, and VA9 between 3 months postoperatively and before surgery in the SPT-TransPRK group (all at P>0.05). There was no significant difference in coma, OSI, MTF cut-off, SR, VA100, VA20, and VA9 between two groups (all at P>0.05).

ConclusionsBoth SMILE and SPT-TransPRK are effective methods for correcting myopia and they have comparable visual quality.Compared with SPT-TransPRK, corneal total HOA and spherical aberration are smaller after SMILE.