Experimental correction of irregular corneal astigmatism using topography-based flying-spot-mode excimer laser photoablation.

Abstract

To present a novel experimental approach for treating irregular corneal astigmatism. After decomposition of topographic analysis data into orthogonal Zernike polynomials, a regular target surface was defined, and the ablation profile was calculated. In a polymethylmethacrylate with an irregular surface, computer-controlled ablation was performed using a 193-nm excimer laser in "flying-spot mode." The difference between flattest and steepest hemimeridians in the 3-mm zone, surface regularity index, and surface asymmetry index were reduced from 8.7 to 1.1 diopters, 1.19 to 0.39, and 1.84 to 0.14, respectively. Tying corneal topography into laser software offers a straightforward concept for correction of irregular corneal astigmatism in an experimental model.