The effect of visual feedback on perceptual and oculomotor performance in a gaze-contingent simulated scotoma paradigm

Abstract

Purpose : Gaze-contingent simulated scotomas have been used in normally-sighted individuals to mimic central vision loss (CVL) and to study perceptual and ocular-motoric processes. We investigated the effect of visual feedback on eccentric viewing training assessed with fixation stability (Bivariate Contour Ellipse Areas, BCEAs), contrast sensitivity(CS) Area-Under-the-Curve(AUC) and acuity(highest visible spatial-frequency).

Methods :
Performance was measured in phases of 25-50 CS trials/session (≧25 correct) in which participants used their peripheral vision to identify 26AFC band-pass-filtered letters. An adaptive algorithm controlled spatial frequency and contrast of the letters. A gaze-contingent binocular scotoma simulated 6°or 9° CVL. Baseline learning (n=8) was measured in six free-viewing trials. Two separate four-phase-protocols investigated two types of visual feedback (target cue, n=10; and scotoma boundary, n=8) across fixation eccentricity and orientation. One freeview session at the start (Phase1) and end (Phase4), and four counterbalanced orientation (eight 45° steps) and eccentricity (6° or 9°) cued sessions with (Phase3) and without (Phase2) visual feedback were performed. Feedback employed letter-surrounding dots (Target-cue) or a scotoma-surrounding ring (scotoma boundary).

Results : Linear regression models identified a significant increase in Acuity (p<0.01) and AUC (p<0.01) and a non-significant trend of BCEAs reduction during baseline. Pre-trial cueing and both feedback types significantly reduced BCEAs (p<0.05) and improved eccentricity-dependent acuity (p<0.05), while AUC results were mixed. Eccentricity-dependent learning was retained in Phase 4 (p<0.05).

Conclusions : Eccentric fixation training delivers sustained functional benefits through both oculomotoric and perceptual learning. The current findings may be transferable into rehabilitation of CVL patients.

This is a 2021 ARVO Annual Meeting abstract.