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Adam Kiefer, Hugo Bruggeman, Russell Woods, William Warren; Obstacle detection during walking by patients with tunnel vision. Journal of Vision 2012;12(9):183. doi: 10.1167/12.9.183.
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"Tunnel vision" (severe peripheral visual field loss), a long-term sequela of visual disorders (e.g., retinitis pigmentosa and choroideremia), causes difficulty detecting and avoiding obstacles during locomotion. We examined the obstacle detection behavior of seven patients (visual fields 6°-27° wide) as they walked to a visible goal in a virtual environment with or without an obstacle present. The obstacle was a short (1.2m) or tall (1.8m) stationary pole appearing at a distance of 4 or 6m from the participant and offset from the straight path between patients’ starting position and the goal by an angle of 1° or 4° (short obstacle) or 1° (tall obstacle). Obstacle and goal poles appeared after participants traveled 1m, and participants pressed a button when they detected an obstacle. Pearson correlations were computed to examine the relation between each participant’s detection rate and their mean trial duration. Significant negative correlations were found between detection rate and trial duration for both the short and tall obstacle (r = -0.79 and -0.76 respectively; p≤.05). Closer examination revealed significant negative correlations between detection rate and trial duration for both the short and tall obstacles at 6m with a 1° offset (r = -0.77 and -0.84, respectively; p≤.05), and a negative trend for the short obstacle at 6m with a 4° offset (r = -0.68, p=.09). No significant relations were found between detection rate and measures of patients’ visual fields or visual acuity (p>.05). These results suggest that patients had greatest difficulty detecting more distant obstacles, and that participants who took more time to try to detect the obstacle actually had lower detection rates. Testing of age-matched controls is in progress and analysis and modeling of the locomotor trajectories are ongoing to simulate patients’ detection and avoidance. The results will help provide a basis for developing interventions for improved mobility.
Meeting abstract presented at VSS 2012
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