Depth of Focus Evaluation for Aspheric IOLs from Optical Raytracing Modeling and Bench Testing

Abstract

Purpose : To investigate the depth of focus of two types of aspheric IOLs using both optical raytracing modeling and physical optical bench testing

Methods : The optical properties associated with depth of focus (DOF) of IOL were evaluated by both optical raytracing modeling and physical bench testing. The optical raytracing simulation was created in Zemax OpticStudio® using a Liou and Brennan model eye with spherical aberration (SA) of 0.21µm at 5mm pupil; and the physical testing setup was developed using a video Modular Transfer Function (MTF) bench (Pilot Group) and a IOL testing model eye (ISO11979-2), which has a model cornea with SA of 0.28 um at 5mm pupil. Two types of aspheric IOLs were used to compared DOF performance in the model eyes. The first IOL has a spherical aberration neutral optic (similar to MX60E IOL from Bausch and Lomb, Inc) and the second IOL has a negative SA optic that fully compensates the positive SA from the cornea (similar to SN60WF IOL, Alcon and ZCB00, J&J). Both subjective (image resolution) and objective (MTF) image metrics were used to evaluate the image quality degradation while various amounts of defocusing was introduced into the optical system.

Results : Using the same amount of defocus, the model eye with the neutral SA IOL showed less image quality degradation when compared to that of the negative SA IOL. The defocus curves from both image resolution and MTF indicate approximately 0.25D ~0.5D of depth of focus improvement with the neutral SA lens.

Conclusions : In both optical raytracing modeling and physical bench testing, the neutral SA IOL improved image quality degradation due to defocusing comparing to that of negative SA IOL. It can be postulated that implanting a neutral SA IOL preserves the inherent positive SA of the cornea and potentially increases depth of focus when compared to implanting a negative SA IOL

This is a 2020 ARVO Annual Meeting abstract.