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N. Parikh, M. S. Humayun, J. D. Weiland; Mobility Experiments With Simulated Vision and Peripheral Cues. Invest. Ophthalmol. Vis. Sci. 2010;51(13):4320.
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© ARVO (1962-2015); The Authors (2016-present)
Aim: To compare performance of normal sighted volunteers using simulated prosthetic vision to navigate through a mobility course with and without a peripheral cueing aid.
Institutional Review Board approval was obtained. 6 normally sighted subjects used an artificial vision simulator set for 60 pixels in the central 14 degrees to navigate through a mobility course. One eye was patched and subjects wore a shroud to block their natural peripheral vision. Subjects were divided into two groups of 3 subjects each. One group received cues towards important objects. The cues were determined using an image processing algorithm and provided upon request as a blinking dot in 1 of 8 directions on the periphery of the simulated pixels. The other group of subjects did not receive cues. Before attempting the mobility course, subjects were trained for 1 session in a different environment to learn the simulated vision and cueing mechanism. They were then tested on different days within one week of each other for 2 sessions each having 15 trials. The mobility course had different objects laid out in a 9.5 m x 2.5 m corridor. Subjects were to find a bright object at the end of the path and then find a sign on the wall in front of them. Objects were rearranged and the sign was moved around in every trial. Time taken to complete the course, total head movements and the number of contacts with objects and errors were recorded.
Total head movements in degrees (on average ~2300 vs. 3200 and number of contacts/errors (3 vs. 5) were significantly less (p<0.05, unpaired t-test) in the cueing group than in the no cueing group. Time was significantly less for the no cueing group (on average 146 vs. 187 seconds). Cueing organizes head movements resulting in significantly less total head movements compared to no cueing when subjects gather information from the surroundings in an unorganized manner. Asking for and getting cues adds time which may explain the increased time with cues. Both groups showed significant learning between the two sessions (p<0.05, paired t-test). The head movements decreased in the cueing group by 25% and in the no cueing group by 43% whereas the time decreased in the cueing group by 28% and in the no cueing group by 36.5%.
Cueing may help individuals with retinal prostheses or low-vision to avoid obstacles. When navigating a mobility course, subjects using cues had less head movements, but required more time to complete the course.
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