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Studies on the feasibility of a subretinal visual prosthesis: data from Yucatan micropig and rabbit

  • Hartmut N. Schwahn
  • Florian Gekeler
  • Konrad Kohler
  • Karin Kobuch
  • Helmut G. Sachs
  • Frank Schulmeyer
  • Wolfgang Jakob
  • Veit-Peter Gabel
  • Eberhart Zrenner
Laboratory Investigation

Abstract.

Background: To estimate the feasibility of the subretinal concept of a visual prosthesis, animal models and prototypes, each representing a certain aspect of the final prosthesis, were utilised to test for requirements for such a medical device: (1) the ability to elicit – by electrical stimulation – event-related central activity in the central visual system, and (2) the long-term biocompatibility and biostability of the implant within the subretinal space. Methods: (1) In rabbit and Yucatan minipig, cortical evoked potentials were recorded with chronically implanted epidural electrodes during stimulation with light flashes as well as during electrical stimulation in the subretinal space. Voltage pulses ranging from –3 V to +3 V were applied via an acutely implanted electrode array on a wired prototype. (2) For biocompatibility studies a silicon-based micro-photodiode array (MPDA) was used that closely resembled the design and composition of the final prosthesis. Fourteen months after implantation, angiography was performed and the histological findings of the retina in the immediate vicinity of the implant were evaluated. Results: (1) In both rabbit and minipig, subretinal electrical stimulation resulted in evoked cortical potentials that were comparable to visual evoked potentials. The lowest threshold levels for the subretinal stimulation were 0.6 V for rabbits and 2 V for minipigs. (2) Long-term stability of an implanted MPDA and its biocompatibility were proven for a postoperative period of 14 months. Conclusions: Data from animal experiments with certain prototypes of the final prosthesis suggest the feasibility of the concept of a subretinal visual prosthesis: Both requirements were met: (1) the functioning of the subretinal stimulation and (2) the biocompatibility of the MPDA implant.

Keywords

Retina Electrical Stimulation Medical Device Voltage Pulse Electrode Array 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Springer-Verlag 2001

Authors and Affiliations

  • Hartmut N. Schwahn
    • 1
  • Florian Gekeler
    • 1
  • Konrad Kohler
    • 1
  • Karin Kobuch
    • 2
  • Helmut G. Sachs
    • 2
  • Frank Schulmeyer
    • 3
  • Wolfgang Jakob
    • 4
  • Veit-Peter Gabel
    • 2
  • Eberhart Zrenner
    • 1
  1. 1.University Eye Hospital Tübingen, Calwerstraße 7/1, 72076 Tübingen, Germany
  2. 2.Eye Hospital, University of Regensburg, Germany
  3. 3.Clinic for Neurosurgery, University of Regensburg, Germany
  4. 4.Clinic for Anesthesiology, University of Regensburg, Germany

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