Optimisation Of A Sectoral Refractive Multifocal Intraocular Lens: Optical Modelling And Bench Evaluation Using Modified Near Segment Geometry

To investigate the optical impact of reducing the near-sector size of a sectoral refractive multifocal intraocular lens (MIOL) from 170° to 120°, with particular emphasis on distance optical quality, decentration tolerance, and robustness to corneal spherical aberration.

University of Plymouth, Cataract and Refractive Surgery Laboratory

Modified sectoral MIOL designs of different angles were first implemented in MATLAB for conceptual design purposes. The finalised 120° design was transferred into OpticStudio for modelling. Corneal spherical aberration (SA) values of 0.00,0.10,0.20,0.28&0.40µm were simulated and performance was evaluated for pupil diameters of 3.0mm & 4.5mm. Decentration was modelled up to ±1.0 mm, into the near and distance segment. Performance metrics included modulation transfer function (MTF), through-focus MTF, point-spread function, and simulated retinal images. Wavelengths of 480nm,546nm&644nm, as well as photopic weighted illumination were used. Optical bench testing was conducted using a Optispherical R&D under matched conditions.

The modified 120° design demonstrated superior distance MTF compared with the 170° design across pupil sizes and corneal SA values, indicating a more distance-dominant optical behaviour. Through-focus analysis demonstrated this distance dominant profile which varied according to levels of decentration: improved distance MTF stability when decentered into the distance segment, with reduced degradation compared to the 170° design, while decentration into the near segment produced predictable and controlled shifts in through-focus performance. Bench testing showed good agreement with computational predictions.

Reducing the near-sector size from 170° to 120° produces a more distance-dominant sectoral multifocal IOL with improved tolerance to decentration and corneal spherical aberration, while maintaining functional near performance. Combined computational modelling and optical bench testing provide a robust framework for optimising asymmetric multifocal IOL designs.