March 2012
Volume 53, Issue 14
Free
ARVO Annual Meeting Abstract  |   March 2012
Evaluation of Electrochemically Treated Bulk Electrodes for STS Retinal Prosthesis by Retinal Optical Imaging
Author Affiliations & Notes
  • Hiroyuki Kanda
    Applied Visual Science,
    Osaka University Graduate School of Medicine, Suita, Japan
  • Takeshi Morimoto
    Applied Visual Science,
    Osaka University Graduate School of Medicine, Suita, Japan
  • Tomomitsu Miyoshi
    Integrative Physiology,
    Osaka University Graduate School of Medicine, Suita, Japan
  • Yoko Hirohara
    Applied Visual Science,
    Osaka University Graduate School of Medicine, Suita, Japan
    Research Institute, Topcon Corporation, Tokyo, Japan
  • Toshifumi Mihashi
    Applied Visual Science,
    Osaka University Graduate School of Medicine, Suita, Japan
    Research Institute, Topcon Corporation, Tokyo, Japan
  • Yasuo Terasawa
    Vision Institute, NIDEK Co Ltd, Gamagori, Japan
  • Kohji Osawa
    Vision Institute, NIDEK Co Ltd, Gamagori, Japan
  • Kohji Nishida
    Ophthalmology,
    Osaka University Graduate School of Medicine, Suita, Japan
  • Takashi Fujikado
    Applied Visual Science,
    Osaka University Graduate School of Medicine, Suita, Japan
  • Footnotes
    Commercial Relationships  Hiroyuki Kanda, None; Takeshi Morimoto, None; Tomomitsu Miyoshi, None; Yoko Hirohara, Topcon (E); Toshifumi Mihashi, Topcon (E); Yasuo Terasawa, NIDEK (E); Kohji Osawa, NIDEK (E); Kohji Nishida, None; Takashi Fujikado, None
  • Footnotes
    Support  The Strategic Research Program for Brain Sciences from the Ministry of Education, Culture, Sports, Science and Technology, Japan.
Investigative Ophthalmology & Visual Science March 2012, Vol.53, 5534. doi:https://doi.org/
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      Hiroyuki Kanda, Takeshi Morimoto, Tomomitsu Miyoshi, Yoko Hirohara, Toshifumi Mihashi, Yasuo Terasawa, Kohji Osawa, Kohji Nishida, Takashi Fujikado; Evaluation of Electrochemically Treated Bulk Electrodes for STS Retinal Prosthesis by Retinal Optical Imaging. Invest. Ophthalmol. Vis. Sci. 2012;53(14):5534. doi: https://doi.org/.

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

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Abstract

Purpose: : We previously developed a novel stimulating electrode for suprachoroidal-transretinal stimulation (STS). It has a higher charge injection capability by enhancing the surface area of platinum electrodes through electrochemical etching (Terasawa et al., ARVO 2010). In this study, we evaluated the activated retinal area by this novel electrode in response to STS using retinal optical imaging.

Methods: : Seven eyes of seven cats were studied. Under general anesthesia, a stimulating electrode array was inserted into the scleral pocket at the posterior pole of the eye. The electrode array comprised two electrochemically treated platinum bulk electrodes (0.5 mm in diameter, 0.3 mm in height). The center-to-center distance between the electrode pair was 1.5 mm. Biphasic pulses (current, 0.03-2.0 mA; duration, 0.5 ms/phase; frequency, 20 Hz) were applied to the retina. Fundus images in the near infrared (800-880 nm) were obtained in every 25 ms for 2 s before, 4 s during, and 20 s after stimulation. By subtracting the pre-stimulus image from the post-stimulus image, a two-dimensional topography of reflectance change was constructed. The impedance of each electrode and optical coherence tomography (OCT) images were also obtained.

Results: : Localized area of reflectance change was observed on and around the stimulating electrode with a threshold current of 0.05 to 1.5 mA. The electrode impedance ranged from 4 to 11 kilo-Ohm. A negative correlation was found between the threshold and the impedance (r = -0.61, p<0.05). In those eyes in which the stimulating electrode attached tightly to the surrounding tissue, as observed by OCT and/or fundus images, the threshold decreased and the impedance increased.

Conclusions: : These results indicate that the novel stimulating electrode is able to localized electrical stimulation to the retina. The threshold current can be decreased if we create a scleral pocket in which the electrodes attach tightly to the surrounding tissue in STS retinal prosthesis.

Keywords: imaging/image analysis: non-clinical • retinal degenerations: hereditary • retina 
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