Higher-order wavefront aberrations induced by small ablation area and sub-clinical decentration in simulated corneal refractive surgery using a perturbed schematic eye model.

The purpose was to investigate the effect of decentered ablation in myopic corneal refractive surgery by simulation. Wavefront aberrations in a small pupil area (radius: 2 mm) for photopic vision and in a large pupil area (radius: 3 mm) for mesopic vision with simulated refractive surgery were analyzed using Zernike polynomials. Radii of ablation were 3, 2.5 and 2 mm. Decentrations of ablation were 0 mm and 0.5 mm. Change of the surface shape by ablation was considered a perturbation, while Gullstrand's schematic eye was used as un-perturbed optics. For photopic vision, wavefront aberrations were about the same as with un-perturbed optics. For mesopic vision, the results were heavily dependent on the radius of ablation area. When the radius was 3 mm, wavefront aberrations did not increase very much compared to un-perturbed optics. When the radius was smaller than 3 mm, spherical aberration was induced by centered ablations, and coma was also induced by decentered ablations. In conclusion, small ablation areas or subclinical decentrations of ablations could cause serious amounts of wavefront aberrations to the optics of the eye in the simulations.