Abstract
Purpose :
Difficulty with seeing faces is a common complaint of individuals with low vision. Seeing faces is most relevant to social interactions, therefore it is critical that we understand face perception in low vision using ecologically relevant procedures. To this end, we used an intuitive measure of “critical viewing distance” (CVD) to assess low vision individuals’ face perception in three tasks: identify matching, emotion discrimination, and visual speech detection.
Methods :
Data were collected from 19 participants with low vision (age 30-88 yrs, 11 with age-related macular degeneration). In three tasks, participants reported 1) whether two faces side-by-side had the same identity, 2) whether a face showed happy, sad, angry, or neutral emotions, and 3) whether a person was talking in a brief silent video. In all tasks, full color face images with 7.1 in height, equivalent to the average length of adult faces, were displayed on a screen on a movable cart. Viewing distances were changed adaptively following a 2-down-1-up rule. CVD were obtained as the maximum viewing distances where the participants completed each task at 71% correct rate.
Results :
Participants’ better eye acuity (BEVA) ranged from 0.18 (20/30) to 1.66 logMAR (20/919). Binocular contrast sensitivity (CS) ranged from 0 to 2.3 logCS. The three CVD were highly correlated with each other (ps < 0.001). However, participants required shorter CVD for emotion discrimination (8.0 ± 3.0 ft) than identity matching (10.1 ± 2.6 ft) or visual speech detection (12.2 ± 2.8 ft) (ps < 0.05). At a social distance of 6 ft away, many participants were not able to recognize identity or emotion but still able to detect visual speech. BEVA and CS were significant predictors for all three CVD (ps < 0.05), and together they explained 57% of the variations in visual speech detection, 48% in identify matching, and 37% in emotion discriminations.
Conclusions :
Low vision affects different face perception tasks differently. Visual speech detection remains robust at distances that are too far for identify matching or emotion discrimination. Critical viewing distance could be a measure of clinical utility for helping patients understand their vision limitations in social context, and the robustness of visual speech detection could be valuable in assisting auditory speech perception in social interactions.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.