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Editors Selection IGR 19-4

Miscellaneous: Strategies to Compensate for Visual Field Impairment

Comment by Pradeep Ramulu on:

78199 Glaucoma-Related Differences in Gaze Behavior When Negotiating Obstacles, Lajoie K; Miller AB; Strath RA et al., Translational vision science & technology, 2018; 7: 10

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In a very nice set of experiments, Lajoie and colleagues examine how glaucoma patients with significant VF damage (better-eye MD =-9 dB) and a slightly younger control group with normal vision navigate a customizable obstacle course. Using a sophisticated set-up, the authors compare how quickly individuals move through the course, how often they contact obstacles they were asked to avoid and, merging head-mounted eye-tracker data with head-mounted video camera data, where they direct their gaze during the mobility task. Both groups were asked to walk the course under normal (undistracted) conditions and also while counting backwards by 3's or while completing a visual search task. For both the distracted and undistracted conditions, glaucoma patients walked slower than controls and were more likely to contact an obstacle. For both groups, gait speed slowed and the number of obstacle contacts increased with distraction. Glaucoma patients also differed from controls with regards to where they set their gaze while navigating the course. Specifically, glaucoma patients directed their gaze more proximal to where they were, and also directed their gaze towards obstacles more than controls. Given that the gaze changes in the glaucoma group did not enable normal walking speeds, and occurred in the context of more obstacle contacts, the authors argue that they were not adaptive, and may be maladaptive. For example, fixating on closer locations makes it harder to route-plan, making overall walking speed slower. It may also result in sharper, more frequent turns, resulting in more collisions. Likewise, fixating on an obstacle may not help avoid the obstacle, as our natural tendency is to move in the direction we look. We hope the authors follow up on this work to determine if altering the gaze patterns of glaucoma patients can prevent falls, and result in safer, more confident glaucoma patients.

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