Comparison of the short-term visual acuity between sub-Bowman’s keratectomy and femtosecond samll incision lenticule extraction

Objective To compare visual acuity and residual diopter after sub-Bowman’s keratectomy (SBK) and femtosecond small incision lenticule extraction (SMILE). Methods In this prospective, non-randomized observational study, 120 eyes of 60 patients were included, 60 eyes of 30 patients received SBK surgery as the SBK group, and 60 eyes of 30 patients received SMILE surgery as the SMILE group . The differences of the visual acuity and residual diopter between the two groups on 1 d, 7 d and 1 month postoperatively were compared. Results At 1 day and 1 week postoperatively, the proportion of uncorrected visual acuity≥1.0 in SBK group were 85.0% and 95.0%, more than that in group SMILE (48.3% and 81.7%), the differences was statistically significant (P=0.000 and 0.023). There were no statistically significant difference in uncorrected visual acuity between SBK (96.7%) and SMILE group (95.0%) at 1 month postoperatively (P=0.648). No statistically significant difference in efficacy index was found between the two groups at 1 month postoperathely(P=0.128). There was no statistically significant difference in safety index between the two groups at 1 month after surgery (P=0.547). At 1 day, 1 week and 1 month postoperatively, the residual diopter in SBK group were (0.376±0.471) D, (0.070±0.413) D and (0.185±0.292) D respectively. In the SMILE group the residual diopter were (-0.073±0.433) D, (0.006±0.338) D and (0.079±0.270) D correspondingly.The residual diopter was statistically significant between the two groups at 1 day、1 month after surgery.There was no statistically significant difference between the two groups at 1 week visit(t=5.439、0.932、2.061, P=0.000、0.353、0.041). Conclusion After SMILE, the consistency of residual diopter and objective diopter are better, but recovery of visual acuity is slightly slower than that of SBK. Key words: Keratomileusis, femtosecond laser; Small incision lens extraction; Visual acuity; Efficacy index; Safety index; Residual diopter, postoperative