Michelle Harter¹ (), J. Patrick Mayo¹, Galen Holland¹, Rakié Cham¹; ¹University of Pittsburgh

People with glaucoma experience progressive visual field loss which leads to significant challenges in maintaining mobility, particularly in complex environments. People with glaucoma may be able to partially compensate for their visual field loss by using a broader range of eye movements to bring important environmental features into their remaining visual field. This work sought to identify differences in eye movements between adults with and without glaucoma while walking through environmental features commonly encountered in daily life. Seven people with glaucoma (69±4 years; 6F; visual field mean deviation better/worse eye: -7.9±6/-10.3±5dB) and seven normal vision controls (63±8 years; 4F) wore eye-tracking glasses (Tobii Pro Glasses 3) while 1. walking straight 6-meter segments, 2. completing 180-degree turns and 3. stepping over obstacles. For each task, eye movement events were identified and measures of fixations (number, average duration) and saccades (average amplitude, scanpath length) were compared between groups using Student’s t-tests. Glaucoma participants had shorter average fixation duration during straight walking (p=0.03), more fixations in obstacle traversals (p=0.05), and smaller saccade amplitudes during turns (p<0.01). For all tasks, glaucoma participants had greater scanpath length than normal vision controls (p≤0.05). The decreased fixation duration, increased fixation number, and increased scanpath length in glaucoma participants indicate that they move their eyes more while walking compared to normal vision controls. However, these increased eye movements are not necessarily indicative of an efficient strategy for gathering environmental information. In fact, the reduced saccade amplitude during turns suggests that their eye movements may be concentrated in a smaller area, rather than indicating a broader range of visual scanning. Further analyses of the spatial patterns and sequences of eye movements in people with glaucoma will be critical for developing training paradigms to promote efficient visual scanning that can allow for safe and independent mobility.

Acknowledgements: Department of Ophthalmology, University of Pittsburgh Hillman Foundation Funds