Smooth pursuit deficits impact dynamic visual acuity in macular degeneration

PURPOSE: In this study, we examine whether the characteristics of smooth pursuit (pursuit gain and placement of the fixational locus relative to the target) change when the task requires dynamic visual acuity.

METHODS: Using the scanning laser ophthalmoscope, we recorded smooth pursuit eye movements in 10 eyes of 6 MD participants and 7 eyes of 4 age-matched controls in response to leftward-or rightward-moving annular targets (O) that briefly (300 milliseconds) changed to a Landolt C at one of several time points during the pursuit trial. Participants were asked to pursue the target and indicate the direction of the C opening.

RESULTS: Individuals with MD had lower pursuit gains and fewer saccades during the C presentation than during the O, compared with their age-matched peers. Further, pursuit gain, but not the distance of the retinal pursuit locus from the target, predicted task performance in the MD group.

CONCLUSIONS: Our findings suggest that compromised pursuit gain in MD participants likely further compromises their dynamic visual acuity and thus ability to view moving targets.