Abstract

Purpose : The pseudophakic eye has generally higher peripheral astigmatism compared to the natural eye, leading to worse peripheral image quality. In this work, peripheral astigmatism of the pseudophakic eye is assessed in vitro using an anatomically equivalent eye model with two different types of intraocular lenses (IOL), by using an instrument based on the double pass principle. The purpose of this work is twofold: to measure peripheral astigmatism in the pseudophakic eye and to evaluate the capability of the double pass instrument to assess peripheral image quality in pseudophakic eyes.

Methods : A water-filled artificial eye was used, including a custom meniscus lens acting as cornea, and a black cardboard acting as fundus, which could pivot around a fixed axis, allowing measuring at field angles of up to 30 degrees. The IOL was supported by its haptics in a receptacle behind a diaphragm. Two IOLs were used in this study: a biconvex hydrophobic acrylic IOL with 20D power (Acrysof SA60AT, Alcon) and an inverted meniscus type hydrophobic acrylic IOL with 22D power (ArtIOL, Art55, Voptica) that reportedly has reduced peripheral astigmatism. Peripheral astigmatism was measured using a custom-made double pass instrument featuring a 780nm laser source, a tunable lens (EL-16-40-TC, Optotune) and a retinal camera (DMM37UX273-ML, The Imaging Source). The instrument can record through focus images of the point spread function. By applying the appropriate processing, defocus and astigmatism at each eccentricity can be calculated.

Results : The fundus’ position of the artificial eye was set at best focus, i.e. the through focus scan using the double pass system returned 0D for both IOLs. Since defocus depends on retinal curvature, which can vary in the population, only peripheral astigmatism was assessed in this study. At 15 degrees astigmatism was measured to be 1.5D and 0D for the Acrysof IOL and the ArtIOL respectively. At 30 degrees astigmatism was found to be 5.65D and 3.5D for the Acrysof IOL and ArtIOL respectively. In all measurements the axis of astigmatism was at 0 degrees when measuring at horizontal field angles.

Conclusions : A novel double pass instrument for the measurement of peripheral image quality was used to measure peripheral astigmatism at 15 and 30 degrees in two IOLs of different type: a biconvex and an inverted meniscus lens. The meniscus lens produced lower astigmatism at all peripheral locations.

This abstract was presented (poster) at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.

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