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 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 6mo, 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 1wk 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 (=0.509). The HOAs increased postoperatively compared with those before surgery in both groups (<0.05). No significant difference in HOA, corneal horizontal coma, spherical aberration, ΔHOA, Δhorizontal coma, and Δspherical aberration were observed between the two group (>0.05). Corneal vertical coma and Δcorneal vertical coma in the FS-LASIK group were higher than those in the SMART group (<0.05). The OSI of both groups at 1mo after surgery was higher than that before surgery (<0.05). At 3 and 6mo postoperatively, the OSI in the FS-LASIK group was slightly higher than that in the SMART group (=0.040 and 0.047, respectively). At 6mo after surgery, the MTF cutoff was statistically significant different between the two groups (=0.026). No significant difference in SR between the FS-LASIK and SMART groups was observed at 1, 3, and 6mo postoperatively (>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.