Optical aberrations induced by sub-clinical decentrations of the ablation pattern

摘要

Purpose: The aim of this work was to study the effect of currently used ablation profiles along with eccentric ablations on the increase of higher order aberrations observed after PRK. Material and Methods: The optical aberrations of 10 eyes were tested before and after PRK. Refractive surgery was performed using a ArF-ecimer laser system. In all cases, the ablation zone was 6 mm or larger. The spherical equivalent of the correction was ranging from -2.5 D to -6.0 D. The measured wavefront error was compared to numerical simulations done with the reduced eye model and currently used ablation profiles as well as compared with experimental results obtained from ablation on PMMA balls. Results: The aberration measurements result in a considerabel change of the spherical- and coma-like wavefront errors. This result was in good correlation with the numericla simulations and the experimentla results. Furthermore, it has been derived that the major contribution on the induced higher order aberrations are a result of the small decentration (< 1.0 mm) of the ablation zone. Conclustions: Higher order spherical- and coma-like aberrations after PRK are mainly determined by the decentration of the ablation zone during laser refractive surgery. Howeve,r future laser systems should use efficient eye-trackign systems and aspherical ablation profiles to overcome this problem.