Glaucoma significantly disrupts gaze-foot coordination and results in less accurate foot placement when precision is required during walking. This may increase the risk of trips and falls in this population.
PurposeSafe navigation requires avoiding objects. Visual field loss may affect how one visually samples the environment, and may thus contribute to bumping into objects and falls. We tested the hypothesis that gaze strategies and the number of collisions differ between people with glaucoma and normally sighted controls when navigating around obstacles, particularly under multitasking situations.MethodsTwenty persons with moderate–severe glaucoma and 20 normally sighted controls walked around a series of irregularly spaced vertical obstacles under the following three conditions: walking with obstacles only, walking and counting backward to simulate a conversation, and walking while performing a concurrent visual search task to simulate locating a landmark. We quantified gaze patterns and the number of obstacle contacts.ResultsCompared with controls, people with glaucoma directed gaze closer to their current position (P < 0.05). They also directed a larger proportion of fixations (in terms of number and duration) to obstacles (P < 0.05). Despite this finding, considerably more people with glaucoma contacted an obstacle (P < 0.05). Multitasking led to changes in gaze behavior in both groups, and this was accompanied by a large increase in obstacle contacts among those with glaucoma (P < 0.05).ConclusionsGlaucoma alters gaze patterns when negotiating a series of obstacles and increases the likelihood of collisions. Multitasking in this situation exacerbates these changes.Translational RelevanceUnderstanding glaucoma-related changes in gaze behavior during walking in cluttered environments may provide critical insight for orientation and mobility specialists and guide the design of gaze training interventions to improve mobility.
Although it has become apparent that cutaneous reflexes can be adjusted based on the phase and context of the locomotor task, it is not clear to what extent these reflexes are regulated when locomotion is modified under visual guidance. To address this, we compared the amplitude of cutaneous reflexes while subjects performed walking tasks that required precise foot placement. In one experiment, subjects walked overground and across a horizontal ladder with narrow raised rungs. In another experiment, subjects walked and stepped onto a series of flat targets, which required different levels of precision (large vs. narrow targets). The superficial peroneal or tibial nerve was electrically stimulated in multiple phases of the gait cycle in each condition and experiment. Reflexes between 50 and 120 ms poststimulation were sorted into 10 equal phase bins, and the amplitudes were then averaged. In each experiment, differences in cutaneous reflexes between conditions occurred predominantly during swing phase when preparation for precise foot placement was necessary. For instance, large excitatory cutaneous reflexes in ipsilateral tibialis anterior were present in the ladder condition and when stepping on narrow targets compared with inhibitory responses in the other conditions, regardless of the nerve stimulated. In the ladder experiments, additional effects of walking condition were evident during stance phase when subjects had to balance on the narrow ladder rungs and may be related to threat and/or the unstable foot-surface interaction. Taken together, these results suggest that cutaneous reflexes are modified when visual feedback regarding the terrain is critical for successful walking.
Two studies were conducted in which compliance to Canadian Hockey Association concussion management guidelines was assessed via response to questionnaires. The first study, conducted in both the 2001 and 2002 hockey seasons, involved elite male and female youth hockey players in the British Columbia Best Ever Program. Over 40% of the under 16-year-old males and 37% of the under 18-year-old females reported having sustained a concussion. In the 2001 male cohort, 18% of the concussions resulted in loss of consciousness (LOC), yet 50% of those indicated they returned to the same game. The second study, involving athletes in the Pacific International Junior Hockey League, indicated that 24% of the 163 athletes sustained a concussion within the last year. Out of the 12 who reported LOC, three of those returned to the same game, while only three were seen by a medical doctor prior to return to play. The results suggest that there remains considerable room for improvement with respect to adherence to return to play guidelines.
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