Modeling the performance of accommodating intraocular lenses

Abstract

Purpose. Pseudo-accommodating intra-ocular lenses (P-IOL) have been available for some time and the availability of accommodating IOL (A-IOL) is imminent. While these types of devices have been tested empirically, few studies have addressed the fundamental parameters governing their performance limits. We modelled the amplitude of accommodation of A-IOLs and P-IOLs to analyse parameters controlling their performance. Methods. Two types of two-element A-IOLs (those with a mobile anterior optical element, or a mobile posterior element) were modelled. Paraxial models were developed to identify key controlling parameters and potential optimal configurations, followed by finite modelling using computer assisted ray-tracing employing equi-convex/concave optical elements. A range of configurations representing varying focal lengths of front and back optical elements were tested. Degenerate cases representing P-IOLs were also tested. Results. P-IOLs have limited rate of pseudo-accommodation with axial shift (approximately 1.2D/mm). For A-IOLs, configurations with positive power front elements returned best rate of accommodation (up to approximately 3.0D/mm when the front element focal length is 25 mm). Conclusions. Considering the maximum potential amounts of axial shifts available, P-IOLs were predicted to provide less than 1D of accommodation whereas A-IOLs may provide up to 3-4D of accommodation, depending on design configuration.