gms | German Medical Science

Artificial Vision 2013

The International Symposium on Visual Prosthetics

08.11. - 09.11.2013, Aachen

Spatial Extent of the Ganglion Cells Response to Subretinal Photovoltaic Stimulation

Meeting Abstract

  • Georges Goetz - Electrical Engineering, Stanford University, Stanford, USA; Hansen Exp. Physics Lab, Stanford University, Stanford, USA
  • D. Palanker - Department of Ophthalmology, Stanford University, Stanford, USA; Hansen Exp. Physics Lab, Stanford University, Stanford, USA
  • R. Smith - Santa Cruz Institute for Particle Physics, University of California Santa Cruz, USA
  • X. Lei - Electrical Engineering, Stanford University, Stanford, USA
  • T. Kamins - Electrical Engineering, Stanford University, Stanford, USA
  • J. Harris - Electrical Engineering, Stanford University, Stanford, USA
  • K. Mathieson - Institute of Photonics, University of Strathclyde, UK
  • A. Sher - Santa Cruz Institute for Particle Physics, University of California Santa Cruz, USA

Artificial Vision 2013. Aachen, 08.-09.11.2013. Düsseldorf: German Medical Science GMS Publishing House; 2014. Doc13artvis12

doi: 10.3205/13artvis12, urn:nbn:de:0183-13artvis129

Published: February 13, 2014

© 2014 Goetz et al.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by-nc-nd/3.0/deed.en). You are free: to Share – to copy, distribute and transmit the work, provided the original author and source are credited.


Outline

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Objective: To assess the spatial extent of the response of the retinal ganglion cells (RGCs) to stimulation by subretinal photovoltaic arrays.

Methods: Photovoltaic arrays with pixel sizes of 140 and 70um were placed on the photoreceptor side of a rat retina, and network-mediated responses of the RGCs were recorded using a 512 electrode array. Stimulation of the individual pixels with 880nm light was used to assess the electrical receptive fields (eRFs) of the individual neurons. Stimulation with visible light was used to map the natural receptive fields (RFs) of the same neurons.

Results: Most of the RGCs responded to 4ms stimulation pulses with latencies in the range of 10-40ms, but some also exhibited delayed responses with latencies of 60-120ms. With 70um pixels, the eRF diameters varied from 120 to 320um for the shorter latency responses, but the delayed component could spread over a 490-560um zone. Average size of the eRFs was 270um, similar to the average size of the natural light responses – 260um. Response to pixels twice as large– 140um – was twice as wide: eRFs were 530um in diameter, on average. There was no correlation between the size of the natural RFs and eRFs in individual neurons.

Discussion: Similarity of the sizes of the electrical receptive fields to natural light responses, as well as the ease of implantation of the wireless arrays and good tolerance of the ocular tissues to the subretinal implant support the promise of the photovoltaic approach to restoration of sight in patients blinded by retinal degenerative diseases.

Acknowledgements: This study was supported by the NIH, AFOSR and BWF CASI