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Michael P. Barry, Gislin Dagnelie, H. Christiaan Stronks, Argus II Study Group; Use of the ArgusTM II Retinal Prosthesis to Augment Auditory Information in a Tracing Task. Invest. Ophthalmol. Vis. Sci. 2011;52(14):4962.
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© ARVO (1962-2015); The Authors (2016-present)
To ascertain the ability of blind subjects to use the ArgusTM II retinal prosthesis to augment information obtained through auditory feedback.
Subjects used a touch screen monitor initially displaying a white circle on a black background. For each trial, subjects attempted to touch the center of the circle and received auditory feedback indicating whether they were successful, within 85 pixels, or beyond 85 pixels of the target center. Upon touching the target, it became the starting location of a white path for the subjects to trace. Auditory cues informed the subject if his or her finger veered outside off the path and when the subject reached the end point. Paths had three straight line segments and two turns with start and end points that were placed at nearly random locations on the screen. Four ArgusTM II subjects performed one to two sets of eight runs of six trials, four with and four without prosthesis stimulation. Each path only appeared once per set of forty-eight trials. One subject had significant natural light perception, and was given eye patches during all trials.
Across all trials, average error in locating the initial circle decreased by 50% when subjects used the ArgusTM II retinal prosthesis, compared to performance without using the prosthesis (p < .001, 2-tailed unpaired t-test). Search time to successfully touch the center of the white circle increased by 44% with prosthesis use (p < .01, 2-tailed t-test). In the tracing part of the task, the time to finish tracing a path increased by 51% with use of the prosthesis, relative to using only auditory feedback (p < .01, 2-tailed t-test). Error in tracing these paths tended to be lower when prosthesis stimulation was provided, but this was not statistically significant.
Use of the ArgusTM II retinal prosthesis improves subjects’ ability to locate targets for hand motions, as seen with the first segment of these experiments. In the tracing segment, when more gross location information was already known to subject, information provided by the prosthesis did tend to augment auditory feedback, but not to statistical significance. Prosthesis use also seems to promote more meticulous scanning and tracing, reflected by the increase in time to find the targets and trace the paths. Data for more complex mazes and additional implant wearers are being collected to further explore these findings.
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