Visually relevant on-bench through-focus analysis of intraocular lenses

Cataract surgery involves the implantation of an intraocular lens (IOL) to replace the opacified crystalline lens. Monofocal IOLs, the most common type, are intended to have the eye in focus at a given distance, usually at infinity. Simultaneous vision IOLs (SVIOLs) and extended depth of focus (EDOF) aim to minimize postoperative dependence on spectacles by providing either multiple foci or an extended depth of focus. These lenses utilize a variety of diffractive and refractive designs to achieve varied focal depths. While common optical testing methods based on the IOL's modulation transfer function (MTF) or resolving power at best focus are essential for quality control, they do not fully address the lenses' performance requirements in daily visual tasks such as reading in a variety of distances. The purpose of this work was to introduce a visually relevant on-bench test method, which includes an image analysis technique and a visual acuity-related image quality metric, to evaluate the through-focus performance of different commercially available IOLs. This method consists of recording a series of optotype images in a realistic eye model with the IOL, adjusting the stimulus vergence through a focus-tunable lens. We compare the results obtained with mono-focal, enhanced mono-focal, EDOF, and (diffractive) trifocal IOLs.