Coordination of Gaze Behavior and Foot Placement During Walking in Persons With Glaucoma

Purpose: Vision normally provides environmental information necessary to direct the foot to safe locations during walking. Peripheral visual field loss limits what a person can see, and may alter how a person visually samples the environment. Here we tested the hypothesis that the spatial-temporal coupling between gaze and stepping in a precision-based walking task is altered in persons with glaucoma, particularly under dual task situations, and results in reduced footplacement accuracy.
Methods: Twenty persons with glaucoma and twenty normally-sighted controls performed a precision walking task that involved stepping to the center of four targets under three conditions: targets only, walking and counting backwards to simulate a conversation, and walking while performing a concurrent visual search task to simulate locating a landmark. We quantified footplacement error and error variability with respect to the targets, as well as saccade and fixation timing with respect to foot placement.
Results: Compared to controls, persons with glaucoma looked earlier at future stepping targets (with respect to toe-off of the foot) in the targets only and count conditions, and transferred gaze away sooner from the current stepping target in all conditions (p < 0.05). Persons with glaucoma also had increased foot-placement error, particularly in the count condition, and increased footplacement error variability compared to normally-sighted controls (p < 0.05).
Conclusions: Glaucoma significantly disrupts gaze-foot coordination and results in less accurate foot placement when precision is required during walking. This may increase the risk of trips and falls in this population.