Abstract
Purpose :
People with central vision loss experience a range of functional deficits, but may not be aware of their scotomas. We evaluate the effect of different types and sizes of simulated gaze-contingent central scotomas (GCS) on young and older participants’ performance for 3 visual functions: visual search, facial recognition, and reading ability.
Methods :
Participants(VA 0 logMAR) and normal MMSE scores were recruited and categorized into 2 groups.Mean age for the young control group(n=8) was 28 years(SD 3.4), and older control group(n=8) was 57 years(SD 4.5). Participants completed 3 tasks with 5 different GCS types: black, invisible, dead leaves, flat noise, and f-1 noise. Participants were randomized to 1 of 3 GCS sizes: 5°, 8°, or 10°.
Eye movements were recorded with a GazePoint Eye tracker used to position the GCS. Face recognition was assessed with a 4AFC match-to-sample task where participants indicated which of 4 Gaussian blurred faces(3 distracters, 1 different target image) matched the identity of an unblurred target. Luminance and chrominance distributions were equated from the average face to eliminate low-level cues.Blur level was controlled by an adaptive staircase to determine threshold blur for 67.5% correct. Visual search was assessed with a conjunction task: participants were required to find a black or white, C or O target among 1-32 distractors. Search times as a function of distractor set size were fit with linear regression. Participants also read a series of MNRead sentences, threshold print size and reading speed were recorded. Visual performance across conditions were compared using 3 way M-ANOVA with Bonferroni correction.
Results :
Older participants had significantly longer initial visual search times(p<0.001), lower reading thresholds(p=0.014) and greater reading speeds(p=0.009) than younger participants. There were no significant differences between GCS types.
There was a significant effect on facial recognition(p=0.05), visual search(p=0.03), initial visual search time(p<0.001), reading threshold print size(p<0.001) and reading speed(p<0.001) with increasing GCS size which worsened performance.
Conclusions :
Increasing GCS size reduced visual performance on all three measures. There was no effect of the type of GCS on visual performance, suggesting that awareness of a scotoma's boundary may not improve eccentric viewing strategies.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.