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Shrinivas Pundlik, Matteo Tomasi, Gang Luo; Evaluation of a Portable Collision Warning Device for Patients With Peripheral Vision Loss in an Obstacle Course. Invest. Ophthalmol. Vis. Sci. 2015;56(4):2571-2579. doi: https://doi.org/10.1167/iovs.14-15935.
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A pocket-sized collision warning device equipped with a video camera was developed to predict impending collisions based on time to collision rather than proximity. A study was conducted in a high-density obstacle course to evaluate the effect of the device on collision avoidance in people with peripheral field loss (PFL).
The 41-meter-long loop-shaped obstacle course consisted of 46 stationary obstacles from floor to head level and oncoming pedestrians. Twenty-five patients with tunnel vision (n = 13) or hemianopia (n = 12) completed four consecutive loops with and without the device, while not using any other habitual mobility aid. Walking direction and device usage order were counterbalanced. Number of collisions and preferred percentage of walking speed (PPWS) were compared within subjects.
Collisions were reduced significantly by approximately 37% (P < 0.001) with the device (floor-level obstacles were excluded because the device was not designed for them). No patient had more collisions when using the device. Although the PPWS were also reduced with the device from 52% to 49% (P = 0.053), this did not account for the lower number of collisions, as the changes in collisions and PPWS were not correlated (P = 0.516).
The device may help patients with a wide range of PFL avoid collisions with high-level obstacles while barely affecting their walking speed.
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