September 2016
Volume 57, Issue 12
Open Access
ARVO Annual Meeting Abstract  |   September 2016
Spatio-temporal characteristics of retinal responses to subretinal photovoltaic stimulation
Author Affiliations & Notes
  • Richard Smith
    Santa Cruz Institute for Particle Physics, UC Santa Cruz, Santa Cruz, California, United States
  • Elton Ho
    Hansen Experimental Physics Lab, Stanford, Palo Alto, California, United States
  • Georges A Goetz
    Hansen Experimental Physics Lab, Stanford, Palo Alto, California, United States
    Electrical Engineering, Stanford, Palo Alto, California, United States
  • Xin Lei
    Electrical Engineering, Stanford, Palo Alto, California, United States
  • Theodore Kamins
    Electrical Engineering, Stanford, Palo Alto, California, United States
  • Jim Harris
    Electrical Engineering, Stanford, Palo Alto, California, United States
  • Keith Mathieson
    Institute of Photonics, University of Strathclyde, Glasgow, United Kingdom
  • Daniel V Palanker
    Hansen Experimental Physics Lab, Stanford, Palo Alto, California, United States
    Ophthalmology, Stanford, Palo Alto, California, United States
  • Alexander Sher
    Santa Cruz Institute for Particle Physics, UC Santa Cruz, Santa Cruz, California, United States
  • Footnotes
    Commercial Relationships   Richard Smith, None; Elton Ho, None; Georges Goetz, None; Xin Lei, None; Theodore Kamins, Pixium Vision (C); Jim Harris, None; Keith Mathieson, None; Daniel Palanker, Pixium Vision (P), Pixium Vision (C); Alexander Sher, None
  • Footnotes
    Support  NIH R01‐EY-018608 (DP)
Investigative Ophthalmology & Visual Science September 2016, Vol.57, 3721. doi:
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    • Get Citation

      Richard Smith, Elton Ho, Georges A Goetz, Xin Lei, Theodore Kamins, Jim Harris, Keith Mathieson, Daniel V Palanker, Alexander Sher; Spatio-temporal characteristics of retinal responses to subretinal photovoltaic stimulation. Invest. Ophthalmol. Vis. Sci. 2016;57(12):3721.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Purpose : To measure the spatio-temporal receptive fields of the retinal ganglion cells activated via subretinal photovoltaic prostheses in degenerate and wild-type rat retinas, and compare them to the natural light responses in healthy retinas.

Methods : Activity of the RGCs was measured in-vitro with a 512 channel multielectrode array. Photovoltaic array with 70µm pixels was placed on the photoreceptor side of healthy and degenerate (RCS) rat retinas. Prosthetic stimulation was performed with 880nm light pulsed at 20Hz and modulated by an LCD displaying binary white noise movies at frame rates of 10Hz and 20Hz. For stimulation of the healthy retina, the same LCD was used to display white noise movies at 30Hz frame rate with continuous visible light illumination. Spatio-temporal receptive fields of the RGCs were measured by calculating the cells’ spiked triggered average (STA) responses to the stimulus.

Results : Significant STA responses to prosthetic stimulation were detected for 10Hz and 20Hz movie frame rates. Prosthetic responses in RCS retinas were classified based on their STAs into two types: eON and eOFF, similar to classification into ON-center and OFF-center types in the healthy retina. The RCS STAs had an average receptive field diameter of 141±11µm and response latency of ~100ms. ON- and OFF-center RGCs in the healthy retina, classified according to their responses to visible light, had response latency of ~180ms. While both ON- and OFF-center RGCs had eON responses to prosthetic stimulation, OFF-center RGCs had half the latency and higher degree of transiency in prosthetic response compared to the ON-center cells. Average receptive field diameter was 239±11µm for visible light and 204±9µm for the prosthetic responses.

Conclusions : Significant prosthetic STA response to white noise movies at 20Hz frame rate indicates that prosthetic vision can operate within a standard range of video frame rates. Spatial receptive fields with prosthetic stimulation in degenerate retinas were smaller than in normal retinas, while these, in turn, were smaller than with natural visual responses in healthy RGCs. Response kinetics were faster with prosthetic stimulation, as expected from the absence of the phototransduction step. Presence of the eON and eOFF responses in the RCS retina demonstrates that prosthetic vision can exhibit some parallel retinal processing even in degenerate retinas.

This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.

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