Abstract
Purpose :
A previous study has shown that pupil transmission apodization can significantly improve through-focus visual performance with spherical aberration by decreasing the impact of peripheral wavefront profiles on retinal image quality. However, this improvement may be limited by the loss of retinal illuminance due to the apodization. The goal of this study is to determine the visual performance benefit of pupil transmission apodization at different luminance levels.
Methods :
A liquid crystal spatial light modulator (SLM) was used to generate pupil transmission apodization profiles described by the Gaussian-type function, e-α (r/r0) ^2, where r0 is the pupil radius and α is the apodization coefficient. This profile was relayed on the eye pupil through an optical system, while subjects performed high contrast visual acuity (VA) and contrast sensitivity (CS) tasks. A baseline condition and three Gaussian pupil apodization profiles (α=1, 3, 7) were tested at three stimulus luminance levels (2.5, 250, and 1000 cd/m2). Each of 16 healthy subjects was dilated with phenylephrine, and a 6 mm artificial pupil was used to maintain a constant retinal illuminance throughout each apodization condition. Visual performance was assessed three times for each condition using a 2AFC QUEST paradigm. A Badal optometer was used to optimize subjects’ focus prior to vision testing, but other aberrations were left uncorrected.
Results :
VA and CS were improved significantly with increasing stimulus luminance for baseline and each apodization condition. For all luminance levels, VA was improved by the medium and high apodization, more than half a line compared to no apodization. Overall, apodization had a greater benefit for CS at higher spatial frequencies. At 4c/deg, visual benefit was only observed with the low apodization at high luminance. For 8 and 16c/deg, medium and high apodization improved CS by a factor of approximately 2 at medium and high luminance levels. However, the high apodization at low light level did not show any improvement at all spatial frequencies due to significant loss in retinal illuminance.
Conclusions :
Gaussian-type pupil transmission apodization was found to be beneficial for VA and CS performance especially at medium and high luminance levels tested in this study. The visual benefit was spatial-frequency dependent, with CS at 4 cpd benefitting the least, and CS at 16 cpd benefitting the most.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.