Abstract
Abstract: :
Purpose: To demonstrate the effect of higher order aberration correction on visual performance in wavefront guided versus conventional laser in situ keratomileusis in myopic adults. Methods: Subjects eligible for LASIK refractive surgery were recruited at two clinical sites for a randomized–eye (patient–masked) study. One eye was randomized to a standard treatment using Planoscan (Conventional) and the fellow eye to customized treatment using Zyoptix (Wavefront guided) on the Bausch & Lomb Technolas 217z laser. Pre–op, 1 week, 1 month, and 3 month visit results were analyzed for thirty–nine subjects. Best spectacle corrected high and low contrast visual acuity was measured using back–illuminated logMAR charts. A Safety Index, defined as the ratio of the post–op and pre–op best corrected visual acuity, was calculated for each visit. Higher order aberrations were measured using the Zywave II WaveFront Aberrometer. Results:The mean (SD) pre–op manifest SE was –4.02DS (1.60) for Planoscan and –4.04 DS (1.52) for Zyoptix. At three months post–op (n=32), mean (SD) manifest SE was –0.06 DS (0.35) for Planoscan and +0.13 DS (0.53) for Zyoptix. The mean (SD) intended optic zone diameter was 6.40 mm (0.19) for Planoscan and 6.62 mm (0.42) for Zyoptix. At three months post–op, the proportion of patients with 20/20 or better (Snellen equivalent) manifest–HC acuity was 94% vs 100% (Planoscan vs Zyoptix) and manifest–LC acuity was 22% vs 34%. Dilated–HC acuity measurement demonstrated a proportion of 81% vs 97% (Planoscan vs Zyoptix), and the dilated–LC acuity task had 3% vs 19%. Dilated–LC acuity tasks demonstrated a clinically significant difference between Planoscan and Zyoptix. The mean (SD) manifest safety index at 3 months was HC: 1.18 (0.22) and 1.27 (0.22), and LC: 1.08 (0.29) and 1.17 (0.25) for Planoscan and Zyoptix respectively. The mean (SD) dilated safety index at 3 months was HC: 1.13 (0.21) and 1.30 (0.28), and LC: 1.02 (0.29) and 1.17 (0.30) for Planoscan and Zyoptix respectively. There was statistically significant difference between Planoscan and Zyoptix for mean dilated HC and LC safety indices (p=0.008 and p=0.046 respectively). Planoscan had statistically and clinically significant higher amount of post–op HORMS (6.0mm) compared to Zyoptix (p=0.007). Planoscan induced significantly more third order aberrations compared to Zyoptix (p<0.001). Conclusions:Zyoptix demonstrated better post–op visual performance compared to Planoscan using LC acuity measurements. Zyoptix provided greater visual safety relative to Planoscan, and had less post–op HORMS.
Keywords: refractive surgery: LASIK • refractive surgery: optical quality • visual acuity