May 2008
Volume 49, Issue 13
Free
ARVO Annual Meeting Abstract  |   May 2008
Reading With a Simulated 60-Channel Retinal Implant
Author Affiliations & Notes
  • J. R. Sommerhalder
    Ophthalmology Clinic, Geneva University Hospital, Geneva, Switzerland
  • A. Perez Fornos
    Ophthalmology Clinic, Geneva University Hospital, Geneva, Switzerland
  • A. B. Safran
    Ophthalmology Clinic, Geneva University Hospital, Geneva, Switzerland
  • M. Pelizzone
    Ophthalmology Clinic, Geneva University Hospital, Geneva, Switzerland
  • Footnotes
    Commercial Relationships  J.R. Sommerhalder, None; A. Perez Fornos, None; A.B. Safran, None; M. Pelizzone, None.
  • Footnotes
    Support  SNF Grant 315200-114152
Investigative Ophthalmology & Visual Science May 2008, Vol.49, 3012. doi:
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    • Get Citation

      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)

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Abstract

Purpose: : To evaluate best possible reading capabilities with a 60-channel retinal implant using simulated artificial vision.

Methods: : 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).

Results: : 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.

Keywords: reading • low vision • shape, form, contour, object perception 
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