Optomechanical eye model with imaging capabilities for objective evaluation of intraocular lenses

PURPOSE: To develop an in vitro procedure providing data on the visual performance obtainable with intraocular lenses (IOLs), for objective comparison between IOL models and direct correlation with the relative visual performance attainable in vivo. SETTING: University Hospital San Raffaele, Milan, Italy. METHODS: An optomechanical eye model was developed to allow simulated in vivo testing of IOLs. The experimental eye mimics the optics and geometry of the Gullstrand's eye model, with an aspheric poly(methyl methacrylate) cornea, variable pupil, and IOL holder. Its detection system is designed to reproduce the mean resolution of the human fovea. The imaging capabilities of the model eye were measured using monofocal IOLs. The tests included qualitative information, such as appearance of optotype chart images, and quantitative information, such as simulated visual acuity tests for far and near distance at variable contrasts. RESULTS: Objective numerical IOL evaluation was made possible on the basis of the visual acuity recorded with the eye model. The maximum recorded far acuity for the monofocal IOLs was about 20/14 at full contrast, progressively decreasing for reduced contrast. Best corrected near acuity ranged between 20/14.7 and 20/15.4. CONCLUSIONS: The optomechanical eye model provided objective grading of IOLs through the evaluation of simulated visual acuity, which can be scaled usefully to human vision. The eye model also allowed the qualitative visualization of IOL imaging properties, making it potentially useful in characterizing and distinguishing different IOL types.