Gaze behavior during obstacle avoidance in individuals with subacute stroke

To investigate the usefulness of entering from the paretic side based on gaze behavior in individuals with stroke during an obstacle avoidance task involving passing through a narrow opening.

Seven individuals with stroke (ages: 57.7 ± 17.4 years) and five healthy controls (ages: 37.0 ± 13.0 years) participated. Participants walked for 4 m and passed through openings matching their shoulder width without collision. They performed this task in six trials (three trials per entry direction). Gaze location and duration were measured using an eye-mark recorder system (EMR-10, NAC Image Technology, Japan). The categories for gaze analysis were as follows: 1) opening, 2) paretic side door (right), 3) non-paretic side door (left), and 4) floor. Visual fixation was defined as a gaze held for 0.1 seconds or longer. The Wilcoxon signed-rank test was conducted to compare entry directions in each category, and the Friedman test was used to compare each gaze category, and multiple comparisons were performed if there were significant differences. The significance level was set at p 0.05.

When entering from the paretic side, the fixation duration was significantly longer on the non-paretic side door (p = 0.028) and shorter fixation on the floor (p = 0.018), with fewer floor fixations overall (p = 0.041). Fixation duration did not differ between the categories in the gaze analysis. However, entering from the non-paretic side resulted in significantly longer floor fixations than that on the non-paretic side door (p = 0.023). No differences were observed between the left and right entrance directions for healthy controls; however, in the comparison of gaze categories, the fixation on the opening was significantly longer (p = 0.004) and more frequent (p = 0.004) than on the floor. 

During passing through the opening task, healthy controls did not look down at the floor. Conversely, individuals with stroke looked down at times. However, when individuals with stroke entered from the paretic side, the time and frequency with which they fixed their gaze on the floor were significantly less than when they entered from the non-paretic side. These results suggest that when entering from the paretic side, participants walked while facing forward, which may have allowed them to spend more time adapting to the objects in the environment and their bodies.

Observing gaze behavior in individuals with stroke may be a useful means of considering adaptation to objects in the environment.