Abstract
Purpose :
While impact of central vision loss(CVL) on fixations and saccadic eye movements is well investigated, little is known about their impact on pursuit eye movements. We explore the role of CVL on pursuit eye movements and evaluate two forms of feedback.
Methods :
8 participants (mean age 66.9, range 35–94 years) with CVL and normal MMSE cognitive status were recruited. All demonstrated binocular CVL on a computerized tangent screen task. Participants pursued a 4° target that moved on a circular path in randomized clockwise or counterclockwise direction at 2.6°/s. Eye movements were measured with an Eyelink 2000Hz eyetracker. Participants were instructed to look above the moving target, simulating an inferior preferred retinal locus(PRL). At random intervals, the pursuit target was replaced for 0.5s with a moving Gabor (σ=1°), whose spatial frequency and contrast were controlled by a QuestPlus algorithm that adaptively converged on the contrast sensitivity function(CSF). Participants indicated if the grating was tilted ±45°.
The role of feedback was explored using i) a CVL awareness condition where the extent of the CVL was revealed using a black gaze-continent circle with ≥diameter as their own CVL; and ii) a gaze-contingent ring whose size dynamically provided feedback concerning PRL placement. Spearman correlations explored associations of clinical measures with pursuit parameters. Repeated measures ANOVA compared outcomes across feedback conditions.
Results :
Mean(SD) binocular visual acuity(VA) was 0.60logMAR(0.24), with a mean CVL radius of 3°(1.3°). Binocular CVL size was significantly correlated with VA(r=0.50, P=0.003), age(r=-0.45, P=0.01) and the mean gain of the pursuit eye movements(r=0.36, P=0.03). VA was also significantly correlated with the mean number of catchup saccades(r=-0.474, P=0.005) and the mean pursuit gain(r=0.50, P=0.003). The accuracy of pursuit was significantly better without CVL awareness feedback(P=0.011). There was no effect of either feedback paradigms on the number of catchup saccades.There was significant interaction of CVL awareness and gaze-contingent feedback on area under the logCSF(P=0.007) with better performance with both forms or without any feedback.
Conclusions :
Smooth pursuit eye movement control is impaired in CVL. However visual feedback training did not improve pursuit accuracy, but may improve contrast sensitivity and provide benefits for vision rehabilitation.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.