Deciphering the best shape aspheric intraocular lens - A raytracing based optimisation study.

Purpose: To develop, implement and demonstrate a calculation strategy to derive the best shape spherical or aspherical intraocular lens (IOL) considering corneal spherical aberration (SA).

Methods: The simulation concept is based on 2D raytracing and involves an ideal plano or spherical wavefront with an optical path length correction which simulates corneal SA. The IOL defined with its equivalent power PIOL, Coddington shape factor (CSF) and edge thickness (ET) could be located with its secondary principal plane (PP2) or its haptic plane (HP) at the predicted axial lens position (ELP).The lens geometry is optimised for the root-mean-squared wavefront error (RMSWF) and the best wavefront and rayscatter focus are derived.

Results: The custom simulation software package is written in Matlab (version 2024a). The applicability of the simulation software is shown with some examples to show the performance of the results. The simulation results are structured to give some insight into best shape spherical and aspheric lenses, the impact of CSF, corneal spherical aberration to be corrected, and the concept of using the ELP to predict either the PP2 or the HP of the lens.

Conclusions: The simulation tool seems to be very robust in optimising best shape spherical and aspherical lenses based on available data for corneal power and spherical aberration. In all examples the spherical aberrations were completely eliminated or reduced to a negligible amount using individually shaped biconvex aspheric IOLs. An implementation in an industrial manufacturing process of customised aspheric lenses and a clinical study are needed to validate the concept in a clinical setting.