Computer modeling of visual impairment caused by intraocular lens misalignment

Purpose: To evaluate a computer program to modulate the visual impairment c aused by intraocular lens (IOL) misalignment and visualize results obtained by numerical calculations. Setting: Department of Ophthalmology, Medical Faculty of Charles University , Prague, Czech Republic. Methods: The optic imagery of a Landolt circle was calculated using a ray-t racing computer program. Visual aberrations resulting from a decentered and /or tilted IOL were studied using this program and compared with theoretica l calculations. Results: The IOL decentration and/or tilt shifted the postoperative refract ive errors I toward myopia and astigmatism (oblique). The combination of IO L decentration and tilt produced a refractive error that depended on the re lationship between the geometrical axes of the decentration and tilt. The r efractive error can be enhanced or diminished depending on the relationship of these axes. Conclusions: These findings verify the results calculated by paraxial verge nce equations. A ray-tracing program simulated the optic imagery for variou s kinds of IOL misalignment and IOL optic properties.