Abstract
Purpose :
Head scanning may be critical for safe walking, especially for patients with homonymous field defects (HFDs). The study investigated differences in head scanning behaviors between left and right HFD.
Methods :
13 patients (7 Left HFD, 6 Right HFD) walked along two urban routes (each about 0.5 miles long) containing among them 7 different street crossing locations without pedestrian signal, while wearing a mobile gaze (eye + head) tracking system that also captured synchronized scene videos. Time points corresponding to street crossing instances (including approach and crossing phases) were manually identified in the scene videos. Large horizontal head scans (> 20°) relative to torso were counted. Based on the direction of crossing traffic (Left, Right, or Both) at each intersection, scanning behavior was classified as either safe – at least one scan towards the direction of traffic, or unsafe – lack of scanning towards the traffic direction. For crossings with 2-way traffic, scanning in both directions were required to be considered as a safe scan. The proportion of crossings with unsafe scanning was compared between Right & Left HFD patients using a Poisson regression model.
Results :
A total of 197 non-signalized crossing instances totaling 55 minutes were annotated, yielding 350 head scans (average of 1.78 scans/crossing). The majority (66%) of crossing instances had one-way traffic (29% from Left and 37% from Right). The proportions of crossing instances with traffic from the left side, right side, and both sides were 30%, 40%, 30%, respectively for Left HFD group, and were 28%, 34% and 38% for Right HFD group, respectively. The proportions of traffic direction experienced was not significantly different between the two patient groups (χ2 = 1.4, p = 0.5). However, the proportion of crossing instances with unsafe scanning in Right HFD patients (0.74) was 62% higher than Left HFD patients (0.46), which was statistically significant (β = 1.62, 95% CI: 1.12 - 2.34, p = 0.01).
Conclusions :
In this study, where direct measurement of head scanning was performed during real-world walking scenarios, Right HFD patients had more instances of unsafe scanning behavior compared to Left HFD patients when crossing non-signalized intersections.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.