VISUAL-ACUITY MODELING USING OPTICAL RAYTRACING OF SCHEMATIC EYES

PURPOSE: We developed a methodology to predict changes in visual perfo rmance that result from changes in the optical properties of the eye. METHODS: Exact raytracing of schematic eyes was used to calculate the point: spread function and the modulation transfer function of the vis ual system. The Stiles-Crawford effect, photopic response, diffraction , and the retinal contrast sensitivity are included in the model, Visu al acuity was predicted by examining the modulation of the resultant r etinal image of a bar target: and by determining when the modulation f alls below a threshold value. Visual acuity was predicted for refracti ve errors ranging from 0 to 5 diopters and for pupil diameters ranging from 0.5 to 8 mm. RESULTS: Visual acuity predictions were compared to clinically found Snellen visual acuities and were found to be highly correlated (r(2) = .909). CONCLUSIONS: This modeling technique shows p romise as a means of evaluating clinical and surgical procedures befor e undertaking clinical trials.