Comparison of asymmetric offset versus pupil centered ablation in refractive surgery

AIM: To compare the visual and optical outcomes following femtosecond laser in situ keratomileusis (FS-LASIK) using an aberration neutral profile with asymmetric offset (AO) and pupil center (PC) treatments. METHODS: In this randomized double-blind clinical trial study, 48 (24 cases) and 38 eyes (19 cases) underwent myopic astigmatism and hyperopic astigmatism LASIK. One eye of each individual was randomly assigned to AO centration and the fellow eye underwent the PC-centered method. The clinical outcomes including uncorrected visual acuity (UCVA), best-corrected visual acuity (BCVA), safety and efficacy indexes, subjective spherical equivalent (SE) and corneal high-order aberrations (HOAs) were measured at baseline and 6mo postoperatively. RESULTS: In the myopic group, the mean preoperative SE and astigmatism were -4.12±0.87 (-2.88 to -6.00) diopter (D) and -0.88±0.79 (0 to -2.75) D, respectively. In the hyperopic group, the mean preoperative SE and astigmatism were 0.93±0.59 (-0.25 to 2.25) D and -0.73±1.00 (0 to -4.25) D, respectively. At 6mo postoperatively, the safety and efficacy indexes were similar for centration in myopic and hyperopic LASIK groups. In the myopic group, significant changes were found in horizontal trefoil (P=0.041) and oblique trefoil (P=0.031) in favor of AO centration treatment. CONCLUSION: Femtosecond-LASIK is a safe and efficacious procedure for treatment of myopic and hyperopic astigmatism. AO-centered and PC-centered approaches provide similar visual and refractive outcomes. Myopic astigmatism LASIK with AO centration leads to slightly better corneal aberration outcomes.