Spherical aberration after laser in situ keratomileusis and photorefractive keratectomy

Abstract

The cornea within the ablation zone becomes more oblate after laser refractive surgery. A mathematical model of the change in asphericity, which accounts for the angle of incidence of the laser beam across the ablation area, predicted this change in spherical aberration. If the model is correct, possible changes in laser algorithms, delivering more ablation to the peripheral optical zone, may better retain the native corneal prolate conformation. Moreover, wavefront-guided ablations may have to consider the effects of fluence variability across the optical zone to fully correct spherical as well as other aberrations.