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J. R. Sommerhalder, A. Perez Fornos, A. B. Safran, M. Pelizzone; Reading With a Simulated 60-Channel Retinal Implant. Invest. Ophthalmol. Vis. Sci. 2008;49(13):3012.
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© ARVO (1962-2015); The Authors (2016-present)
To evaluate best possible reading capabilities with a 60-channel retinal implant using simulated artificial vision.
Four normal volunteers performed full-page text reading tasks under conditions simulating a 60-channel retinal implant. A low resolution viewing window containing 60 pixels was stabilized in the central visual field using a high speed eye and head tracking system. Two parameters were varied in order to reach best possible reading performance: (1) the number of pixels covering the height of the lowercase character ‘x’ (spatial resolutions from 2.6 to 9 pixels/char) and (2) the orientation of the viewing window (horizontal 10x6 or vertical 6x10 pixels). Performance was measured in terms of reading scores (% of correctly read words) and reading rates (words/min).
Maximum reading performances were attained at spatial resolutions between 3.6 and 6 pix/char. Below and above this range, performance declined. In optimal viewing conditions, reading scores were perfect or close to perfect (>85%). Important individual differences were measured for reading rates. The best subject achieved maximum reading rates of 35-40 words/min in the most favorable conditions. Individual reading rate peaks were quite narrow and situated at slightly different spatial resolutions. Due to learning effects, no clear advantage could be found for either viewing window orientation: subjects generally performed worse in the first measured condition.
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