April 2014
Volume 55, Issue 13
Free
ARVO Annual Meeting Abstract  |   April 2014
Evaluation of long-term implantation of an inactive 49-channel electrode array for STS retinal prosthesis
Author Affiliations & Notes
  • Hiroyuki Kanda
    Applied Visual Science, Osaka Univ Graduate Sch of Med, Suita, Japan
  • Takeshi Morimoto
    Applied Visual Science, Osaka Univ Graduate Sch of Med, Suita, Japan
  • Yasuo Terasawa
    Vision Institute, NIDEK Co Ltd, Gamagori, Japan
  • Yukari Nakano
    Vision Institute, NIDEK Co Ltd, Gamagori, Japan
  • Kohji Nishida
    Ophthalmology, Osaka Univ Graduate Sch of Med, Suita, Japan
  • Takashi Fujikado
    Applied Visual Science, Osaka Univ Graduate Sch of Med, Suita, Japan
  • Footnotes
    Commercial Relationships Hiroyuki Kanda, None; Takeshi Morimoto, None; Yasuo Terasawa, NIDEK Co Ltd (E); Yukari Nakano, NIDEK Co Ltd (E); Kohji Nishida, None; Takashi Fujikado, None
  • Footnotes
    Support None
Investigative Ophthalmology & Visual Science April 2014, Vol.55, 1814. doi:
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    • Get Citation

      Hiroyuki Kanda, Takeshi Morimoto, Yasuo Terasawa, Yukari Nakano, Kohji Nishida, Takashi Fujikado; Evaluation of long-term implantation of an inactive 49-channel electrode array for STS retinal prosthesis. Invest. Ophthalmol. Vis. Sci. 2014;55(13):1814.

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

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Abstract
 
Purpose
 

We developed a second-generation device for STS (Suprachoroidal-Transretinal Stimulation) retinal prostheses. The electrode array of this device comprises 49 stimulating electrodes and a multiplexer IC-chip. To verify its safety, we investigated its effects following chronic implantation for 6 months.

 
Methods
 

Inactive devices were used to assess chronic implantation (Fig. 1). These implants include a multiplexer and an electrode array of 49-channel porous electrodes (diameter, 0.5 mm; height, 0.3 mm). Three eyes of 3 pigmented rabbits were used. We created a scleral pocket at the posterior pole of the eye and inserted the electrode array. Implants were implanted for 6 months without electrical stimulation. Fundus photography, fluorescein angiography (FA), indocyanine green angiography (IA), optical coherence tomography (OCT), and slit-lamp examination were performed at 1 week, 1 month, 3 months, and 6 months after implantation. After the experiment was concluded, the eyes were enucleated, and the retinas were stained with hematoxylin and eosin and examined by light microscopy.

 
Results
 

OCT (Fig. 2), FA, IA, and histological examination at 6 months after implantation revealed no significant changes in the retinal areas (49 × 3 = 147 areas) where the electrodes were located. No retinal damage, including retinal edema, retinal detachment, ischemia in choroidal circulation, or FA leakage, was identified. Furthermore, no conjunctival dehiscence or erosion was observed at the location of the multiplexer. At the center of the array, the thickness of the residual sclera on the electrodes significantly decreased from 103 ± 28 μm to 74 ± 29 μm (mean ± SD) (p < 0.01, n = 3, paired t-test) during 6 months of implantation.

 
Conclusions
 

These results indicate that the electrode array of a second-generation device for STS retinal prosthesis is safe for chronic implantation. Moreover, during chronic implantation, the distance between the electrode and the retina decreased with the thinning of the sclera, thereby suggesting that phosphene threshold might be decreased by chronic implantation.

 
 
The implant (scale bar = 1 mm)
 
The implant (scale bar = 1 mm)
 
 
Optical coherence tomography image after 6 months of implantation
 
Optical coherence tomography image after 6 months of implantation
 
Keywords: 688 retina • 696 retinal degenerations: hereditary • 584 low vision  
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