Comparative study of objective visual quality between FS-LASIK and SMART in myopia

AIM:To compare the changes in the objective visual quality of patients with low and moderate myopia postoperatively after transepithelial photorefractive keratectomy using the smart pulse technology(SMART)and femtosecond laser in situ keratomileusis(FS-LASIK).METHODS:Corneal higher-order aberrations(HOAs),horizontal coma,vertical coma and spherical aberration were measured using Pentacam,and cutoff for modulation transfer function(MTF cutoff),objective scatter index(OSI)and Strehl ratio(SR)was measured using an optical quality analysis system(OQAS-II),before and after operation at 1,3,and 6 mo,and data were analyzed by repeated measurement two-way analysis of variance.RESULTS:The difference in uncorrected distance visual acuity between SMART and FS-LASIK was statistically significant only 1 wk postoperatively.Approximately 86.36%and 80.69%of patients with spherical equivalent(SE)in±0.50 D were observed in the SMART and FS-LASIK groups,respectively.No significant difference was observed in SE between the two groups(P=0.509).The HOAs increased postoperatively compared with those before surgery in both groups(P<0.05).No significant difference in HOA,corneal horizontal coma,spherical aberration,ΔHOA,Δhorizontal coma,andΔspherical aberration were observed between the two group(P>0.05).Corneal vertical coma andΔcorneal vertical coma in the FS-LASIK group were higher than those in the SMART group(P<0.05).The OSI of both groups at 1 mo after surgery was higher than that before surgery(P<0.05).At 3 and 6 mo postoperatively,the OSI in the FS-LASIK group was slightly higher than that in the SMART group(P=0.040 and 0.047,respectively).At 6 mo after surgery,the MTF cutoff was statistically significant different between the two groups(P=0.026).No significant difference in SR between the FS-LASIK and SMART groups was observed at 1,3,and 6 mo postoperatively(P>0.05).CONCLUSION:The HOAs increase and visual quality is delayed in both groups postoperatively,and the long-term objective visual quality after SMART is slightly better than that after FS-LASIK.