caa a22 4500 46912279X CHVBK 20180323133143.0 cr unu---uuuuu 170328e19920701xx s 000 0 eng 10.1007/BF02368135 doi (NATIONALLICENCE)springer-10.1007/BF02368135 Simulation of a phosphene-based visual field: Visual acuity in a pixelized vision system [Elektronische Daten] [Kichul Cha, Kenneth Horch, Richard Normann] A visual prosthesis for the blind using electrical stimulation of the visual cortex will require the development of an array of electrodes. Passage of current through these electrodes is expected to create a visual image made up of a matrix of discrete phosphenes. The quality of the visual sense thus provided will be a function of many parameters, particularly the number of electrodes and their spacing. We are conducting a series of psychophysical experiments with a portable "phosphene” simulator to obtain estimates of suitable values for electrode number and spacing. The simulator consists of a small video camera and monitor worn by a normally sighted human subject. To simulate a discrete phosphene field, the monitor is masked by an opaque perforated film. The visual angle subtended by images from the masked monitor is 1.7° or less, depending on the mask, and falls within the fovea of the subject. In the study presented here, we measured visual acuity as a function of the number of pixels and their spacing in the mask. Visual acuity was inversely proportional to pixel density, and trained subjects could achieve about 20/26 visual acuity with a 1024 pixel image. We conclude that 625 electrodes implanted in a 1 cm by 1 cm area near the foveal representation of the visual cortex should produce a phosphene image with a visual acuity of approximately 20/30. Such an acuity could provide useful restoration of functional vision for the profoundly blind. Pergamon Press Ltd., 1992 Phosphene simulation nationallicence Visual prosthesis nationallicence Visual acuity nationallicence Cha Kichul Department of Bioengineering, University of Utah, 84112, Salt Lake City, UT aut Horch Kenneth Department of Bioengineering, University of Utah, 84112, Salt Lake City, UT aut Normann Richard Department of Bioengineering, University of Utah, 84112, Salt Lake City, UT aut Annals of Biomedical Engineering Kluwer Academic Publishers 20/4(1992-07-01), 439-449 0090-6964 20:4<439 1992 20 10439 https://doi.org/10.1007/BF02368135 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF02368135 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Cha Kichul Department of Bioengineering, University of Utah, 84112, Salt Lake City, UT aut NATIONALLICENCE 700 1- Horch Kenneth Department of Bioengineering, University of Utah, 84112, Salt Lake City, UT aut NATIONALLICENCE 700 1- Normann Richard Department of Bioengineering, University of Utah, 84112, Salt Lake City, UT aut NATIONALLICENCE 773 0- Annals of Biomedical Engineering Kluwer Academic Publishers 20/4(1992-07-01), 439-449 0090-6964 20:4<439 1992 20 10439 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer