Modeling the Impact of Pupil Transmission Apodization on Visual Performance under Different Illumination Levels

Abstract

Purpose : By masking the peripheral wavefront aberrations, pupil transmission apodization can reduce wavefront aberration root-mean-square (RMS) across pupil area and improve retinal image quality. However, the apodized filter also reduces the overall pupil illumination and thus decreases the patient’s neural response or neural contrast sensitivity function (NCSF), which will limit the retinal image quality improvement. The study aims to investigate the interplay among pupil size, illumination, and apodization profiles.

Methods : Gaussian-type apodization functions were designed, e^{-α (r/r}₀^{) ^2}, where r₀ is the pupil radius and α is the apodization coefficient. A Monte-Carlo method-based simulation was conducted to investigate the averaged visual correction performance improvement (comparing with a baseline condition) of three Gaussian pupil apodization profiles (α=1, 3, 7) under different stimulus luminance levels (1000, 250 and 2.5 cd/m²). A total of 10 single-vision patients’ wavefronts were generated based on our vision model. The visual correction performance was evaluated using an area MTF (aMTF) based visual acuity (VA) computation model.

Results : With 1000 cd/m² illumination, consistent VA improvements are observed with stronger apodization. Comparing the baseline or filter-free case, the simulated logMAR-VA improvements are -0.03, -0.05, and -0.06 for α=1, 3, and 7 filter designs, respectively for 6-mm pupil size. With 250 cd/m² illumination or typical room light condition, the strongest VA improved was observed with α=3 apodization condition. The simulated logMAR-VA improvements are -0.03, -0.05, and -0.03, respectively, with α=1, 3, and 7 filter designs comparing with the baseline. Under 2.5 cd/m², the VA benefit is not observed in the simulation.

Conclusions : The VA benefit of Gaussian-type pupil transmission apodization filters is simulated. With photopic illumination, VA benefits are observed with apodization filters, and more than half-line VA improvement is achieved. The VA improvement is mainly due to wavefront aberration (such as spherical aberration) RMS reduction across pupil area. The performance improvements were compromised under lower-illumination condition due to the reduced neural response.

This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.