June 2013
Volume 54, Issue 15
Free
ARVO Annual Meeting Abstract  |   June 2013
Reducing the Number of Stimulators and Electrical Tracks in High-Resolution Visual Prostheses
Author Affiliations & Notes
  • Milan Djilas
    Institut de la Vision, INSERM/UPMC Univ Paris 6/CNRS/CHNO des XV-XX, Paris, France
  • Ryad Benosman
    Institut de la Vision, INSERM/UPMC Univ Paris 6/CNRS/CHNO des XV-XX, Paris, France
  • Philippe Bergonzo
    LIST, CEA, Saclay, France
  • Christoph Posch
    Institut de la Vision, INSERM/UPMC Univ Paris 6/CNRS/CHNO des XV-XX, Paris, France
  • Jose Sahel
    Institut de la Vision, INSERM/UPMC Univ Paris 6/CNRS/CHNO des XV-XX, Paris, France
    Fondation Ophtalmologique Adolphe de Rothschild, Paris, France
  • Serge Picaud
    Institut de la Vision, INSERM/UPMC Univ Paris 6/CNRS/CHNO des XV-XX, Paris, France
    Fondation Ophtalmologique Adolphe de Rothschild, Paris, France
  • Footnotes
    Commercial Relationships Milan Djilas, None; Ryad Benosman, None; Philippe Bergonzo, None; Christoph Posch, None; Jose Sahel, UPMC/Essilor (P), Second Sight (F); Serge Picaud, UPMC (P), Pixium Vision (C)
  • Footnotes
    Support None
Investigative Ophthalmology & Visual Science June 2013, Vol.54, 1064. doi:
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      Milan Djilas, Ryad Benosman, Philippe Bergonzo, Christoph Posch, Jose Sahel, Serge Picaud; Reducing the Number of Stimulators and Electrical Tracks in High-Resolution Visual Prostheses. Invest. Ophthalmol. Vis. Sci. 2013;54(15):1064.

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

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Abstract
 
Purpose
 

Retinal diseases such as RP and AMD cause photoreceptor degeneration while other cell layers partially remain. Retinal prostheses restore useful vision by activating these cells. The NxN electrode matrix and stimulators are coupled with N2 electrical tracks. With the increase of pixel resolution, this inter-connection becomes difficult to fabricate. The foil also becomes more rigid, making the implantation surgery more challenging. Here we propose an alternative electrode design and connectivity layout that significantly reduces the required number of metal tracks and stimulators.

 
Methods
 

The proposed layout is shown on Figure 1. To stimulate a particular pixel, segments from one row, one column and two diagonals containing that pixel are activated simultaneously. To excite only the tissue at the target pixel, the stimulation intensity of each active segment is kept below threshold, whereas the intensity of simultaneous activation of four active segments at the target pixel is above threshold.

 
Results
 

The proposed layout requires a total of 6(N-1) electrical tracks and only 4 stimulators (1 for row, 1 for column, and 2 for diagonals) regardless of implant resolution. One additional track is needed for a common counter-electrode. Finite-element method simulations clearly confirm significantly higher stimulation intensity at the target pixel compared to other pixels stimulated with 4x lower intensity. This range should be sufficient to activate only the former.

 
Conclusions
 

The proposed strategy requires 6N-5 tracks and 4 stimulators, compared to N2+1 tracks and N2 stimulators in the standard one-track-per-electrode layout. The downside of such an approach is that only a single pixel at a time can be activated. This would however not be a limiting factor if asynchronous image acquisition is implemented. Future work includes experimental validation of the proposed strategy.

 
 
Figure 1 A 5x5 electrode layout with 4 stimulating electrodes per pixel. Segments designated with the same number are electrically connected. Simultaneous electrical stimulation through segments from one column (segments 7), one row (segments 2), and two diagonals (segments 14 for \ and 19 for /) produces maximal stimulation in the target pixel located in the intersection of the four lines (thick outline). A metalized grid surrounding the electrodes serves as the counter-electrode.
 
Figure 1 A 5x5 electrode layout with 4 stimulating electrodes per pixel. Segments designated with the same number are electrically connected. Simultaneous electrical stimulation through segments from one column (segments 7), one row (segments 2), and two diagonals (segments 14 for \ and 19 for /) produces maximal stimulation in the target pixel located in the intersection of the four lines (thick outline). A metalized grid surrounding the electrodes serves as the counter-electrode.
 
Keywords: 688 retina  
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