Delivery of Information and Power to the Implant, Integration of the Electrode Array with the Retina, and Safety of Chronic Stimulation

  • James Loudin
  • Alexander Butterwick
  • Philip Huie
  • Daniel Palanker


The fundamental function of a visual prosthesis is to deliver information about a patient’s surroundings to his/her neurons, usually via patterned electronic stimulation. In addition to transmitting visual information from the outside world to the implanted stimulating array, visual prostheses must also pass the electrical power necessary for such stimulation from the external world to the intraocular electrode array. The first section of this chapter reviews three common methods for achieving this data and power transfer: direct wireline connections (suitable for research studies), inductively coupled coils, and photodiode-based optical systems which utilize the natural optics of the eye.

Once the data and power has been received, retinal prostheses must effectively deliver stimulation currents to surviving retinal neurons. This necessitates an understanding of the electrode/retina interface. The second section of this chapter is a histological description of this interface for the case of subretinal implants, investigating the tissue response to flat implants coated with different materials. Several three-dimensional geometries are also described and evaluated to decrease the implant–neuron distance.

Finally, stimulation currents must not damage the stimulated neurons. The third section of this chapter describes measurements and scaling laws associated with tissue damage from electric currents. Damage thresholds are found to be approximately 50–100 times stimulation thresholds.


Cochlear Implant Damage Threshold Inner Nuclear Layer Subretinal Space Stimulation Threshold 
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.



Alternating current


Artificial silicon retina, a retinal prosthesis fabricated by Optobionics


Combined metal on silicon


Computational molecular phenotyping


Direct current


European Union


Intelligent medical implants, a company fabricating a retinal prosthesis


Inner nuclear layer




Liquid crystal display


Microphotodiode array, retinal prosthesis fabricated by retina implant AG


Outer nuclear layer


45 days after birth


Propidium iodide

RCS rat

Royal College of Surgeons rat, a common animal model of retinal degeneration


Radio frequency


Retinal pigmented epithelium


Sputtered iridium oxide film


A photo-curable epoxy


University of Southern California


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Copyright information

© Springer Science+Business Media, LLC 2011

Authors and Affiliations

  • James Loudin
    • 1
  • Alexander Butterwick
  • Philip Huie
  • Daniel Palanker
  1. 1.Department of Applied PhysicsStanford UniversityStanfordUSA

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