Abstract
Purpose :
Pupil independency ensures consistent performance over a range of lighting conditions, which is important for monofocal intraocular lenses (IOLs). In-vitro measurements are often used to assess the quality of IOLs, but different metrics are used that can give different results. In this study we evaluated the distance performance for different pupil sizes using optical bench data of monofocal IOLs with different optical designs.
Methods :
Through-frequency modulation transfer function (MTF) and phase transfer function were measured with an optical bench to assess optical behavior at 2, 3, 4 and 5mm pupil in green and white light, using a corneal eye model that resembles the average chromatic and spherical aberration (SA) of the human eye. Binocular simulated visual acuity (sVA) and weighted Optical Transfer Function (wOTF) were calculated using a method described in the literature, which has been found to be clinically relevant (Alarcon BOE 2016). Four different monofocal IOLs were included in the assessment: an aspheric IOL (A1) that fully compensates for average corneal SA, a higher-order aspheric (HA) IOL designed to improve intermediate vision with one line as compared to A1, while providing full compensation of corneal SA, an aspheric IOL (A2) that partially compensates for corneal SA, and a spherical IOL (S) with positive SA. To investigate the pupil dependency all metrics were normalized for each lens model to the corresponding value at 3mm.
Results :
Many of the IOLs showed a large pupil dependency for green light at 100c/mm, either for 2mm or 5mm. Analysis of the wOTF showed that for 2mm pupil the pupil dependency is vastly reduced (ranging between 96 and 113%), while for larger pupils the dependency mostly occurs for IOLs with residual SA, reducing the wOTF at 5mm to 42% for IOL model S. The sVA showed that at 2mm all IOL models have the same performance (with up to 1 letter of difference with respect to 3mm). Consistent with the wOTF metric, sVA for 5mm pupil resulted in greater pupil dependency for the designs with residual SA, with up to 1 line of difference with respect to 3mm for IOL model S.
Conclusions :
The pupil dependency that is observed in green light conditions is not reflected in other metrics that are shown to be clinically relevant, except for a large degradation in image quality for large pupil sizes with IOLs that do not fully compensate for spherical aberration.
This is a 2020 ARVO Annual Meeting abstract.