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Author Notes:

Maureen A. McCall: 301 E. Muhammad Ali Blvd, Louisville, KY 40202, mo.mccall@louisville.edu, Phone: 502-852-3386

The authors would like to thank Drs. B. Borghuis, A. Sher, and J. Loudin for comments and insight on the manuscript.

The authors declare no competing financial interests.

Subjects:

Research Funding:

This work was supported by NIH Grant EY018608 (MTP and MAM) an unrestricted grant from Research to Prevent Blindness (MAM); Department of Veterans Affairs Research Scientist Award (MTP); and NIH T32 Grant 5 T32 HL 76138-09 (JWF).

Keywords:

  • Science & Technology
  • Technology
  • Life Sciences & Biomedicine
  • Engineering, Biomedical
  • Neurosciences
  • Engineering
  • Neurosciences & Neurology
  • retina
  • prosthesis
  • photovoltaic
  • retinitis pigmentosa
  • artificial vision
  • ELECTRICAL-STIMULATION
  • GANGLION-CELLS
  • SUPERIOR COLLICULUS
  • PHOTORECEPTOR DEGENERATIONS
  • MACULAR DEGENERATION
  • RATS
  • RESPONSES
  • THRESHOLDS
  • MECHANISMS
  • AGE

Local signaling from a retinal prosthetic in a rodent retinitis pigmentosa model in vivo

Tools:

Journal Title:

Journal of Neural Engineering

Volume:

Volume 11, Number 4

Publisher:

, Pages 046012-046012

Type of Work:

Article | Post-print: After Peer Review

Abstract:

Objective: In clinical trials, retinitis pigmentosa patients implanted with a retinal prosthetic device show enhanced spatial vision, including the ability to read large text and navigate. New prosthetics aim to increase spatial resolution by decreasing pixel/electrode size and limiting current spread. To examine spatial resolution of a new prosthetic design, we characterized and compared two photovoltaic array (PVA) designs and their interaction with the retina after subretinal implantation in transgenic S334ter line 3 rats (Tg S334ter-3). Approach: PVAs were implanted subretinally at two stages of degeneration and assessed in vivo using extracellular recordings in the superior colliculus (SC). Several aspects of this interaction were evaluated by varying duration, irradiance and position of a near infrared laser focused on the PVA. These characteristics included: activation threshold, response linearity, SC signal topography and spatial localization. The major design difference between the two PVA designs is the inclusion of local current returns in the newer design. Main results: When tested in vivo, PVA-evoked response thresholds were independent of pixel/electrode size, but differ between the new and old PVA designs. Response thresholds were independent of implantation age and duration (≤7.5 months). For both prosthesis designs, threshold intensities were within established safety limits. PVA-evoked responses require inner retina synaptic transmission and do not directly activate retinal ganglion cells. The new PVA design evokes local retinal activation, which is not found with the older PVA design that lacks local current returns. Significance: Our study provides in vivo evidence that prosthetics make functional contacts with the inner nuclear layer at several stages of degeneration. The new PVA design enhances local activation within the retina and SC. Together these results predict that the new design can potentially harness the inherent processing within the retina and is likely to produce higher spatial resolution in patients.

Copyright information:

© 2014 IOP Publishing Ltd.

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