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X.-Y. Chai, L.-L. Zhang, F. Shao, C.-Q. Zhou, K.-J. Wu, Q. Ren; Tactile Based Phosphene Positioning System for Visual Prosthesis. Invest. Ophthalmol. Vis. Sci. 2007;48(13):662.
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© ARVO (1962-2015); The Authors (2016-present)
Accurate phosphene positioning is crucial for examining and training of the blind people after visual prosthesis implantation. In this abstract, we report a development of the tactile based phosphene positioning system (PPS) for accurately detecting the induced phosphene position in the space and evaluate the accuracy and reproducibility of such system.
The PPS is consisted of a chin rest to stabilize the head movement and a computer controlled touch screen system topped with a tactile guided disc. The touch screen system is used to record the electrically stimulated phosphene location by screen touch with tester’s finger. A tactile guided disc with labeled longitude and latitude dots is used on top of the touch screen system to provide the spatial guidance for the blind tester. To study the accuracy and reproducibility of such a system, a head mounted display (HMD) system is used to simulate the electrically induced phosphenes both in near visual field and far visual field for the normal sighted volunteers. Twenty volunteers with age range 24 to 30 are recruited in the study. The left index finger is fixed in the middle of the touch screen and the right index finger can indicate the position of phosphenes by touching the screen. Training is performed before the actual trial so that the volunteer could orient themselves in PPS. The time between the appearance of simulated phosphene on the HMD and the identified position recorded by screen touch was recorded by a timer. The experiment with and without tactile guide disc are performed and the results are compared.
The reproducibility has no significant difference with and without tactile guide disc, while the accuracy with guide disc is remarkably increased compared to the one without guide disc. Positioning of phosphenes in near visual field is more accurate than in far visual field in both modes. The accuracy is observed to be enhanced after the experiment goes further, while the judging time for volunteers to position phosphenes also gets shorter.
Tactile based method in phosphenes positioning is highly recommended because of reproducibility. Using tactile guided disc and scientific training can improve the accuracy of phosphene positioning.
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