Initial Evaluation of the Safety and Durability of Retinal Prostheses Based on Suprachoroidal–transretinal Stimulation using Bullet-shaped Platinum Electrodes

• Tashiro Hiroyuki

  Department of Health Sciences, Faculty of Medical Sciences, Kyushu University Graduate School of Materials Science, Nara Institute of Science & Technology

• Terasawa Yasuo

  Vision Institute, Nidek Co., Ltd. Graduate School of Materials Science, Nara Institute of Science & Technology

• Kuwabara Mariko

  Department of Health Sciences, Faculty of Medical Sciences, Kyushu University

• Osawa Koji

  Vision Institute, Nidek Co., Ltd.

• Tokuda Takashi

  Graduate School of Materials Science, Nara Institute of Science & Technology

• Ohta Jun

  Graduate School of Materials Science, Nara Institute of Science & Technology

• Fujikado Takashi

  Applied Visual Science, Osaka University Graduate School of Medicine

抄録

We have developed retinal prosthetic devices based on suprachoroidal-transretinal stimulation (STS). The effectiveness and safety of such novel devices are confirmed by in vitro and in vivo tests based on scientific knowledge. Animal testing is especially important because it demonstrates the total safety of the device. We successfully developed a long-term evaluation system with automatic stimulation and measurement of electrochemical characteristics in freely moving rabbits. This system allows evaluation of long-term safety and change in electrochemical characteristics. In addition, we conducted a pilot evaluation of the safety of STS using bullet-shaped electrodes in rabbits. No obvious injuries were observed in all examinations. However, the array moved away from the retina in a few rabbits. Visual and electrical evoked potentials (EEPs) were recorded after three-month implantation. The function of the retinal neurons around the electrode is assumed to be maintained because EEPs were observed after three-month stimulation. However, the evoked potentials become indistinct with time in some rabbits. The development of implantable recording electrode capable of long-term evaluation is necessary for assessing the function of retina exposed to electrical stimulation. Long-term safety and change in electrochemical characteristics can be confirmed easily using this system. No histological difference was observed between the active and inactive electrodes, suggesting that the amount of charge used in the study can be safely injected. The charge injection capacity (CIC) of these electrodes provides an indication of the safety threshold for STS. The electrode array should have a curvature to fit the eyeball to avoid movement of the array away from the retina. The electrode height is slightly greater compared to the sclera thickness. Accordingly, methods to enhance the CIC vs. geometrical surface area are required if the electrode height is reduced. We were able to obtain an indication of the required performance for the stimulation electrode based on the safe charge injection for STS (CIC of approximately 90 μC/cm² in PBS) and establish a system capable of evaluating safety and durability of retinal prostheses for long-term stimulation.

収録刊行物

• Advanced Biomedical Engineering

  Advanced Biomedical Engineering 6 (0), 8-14, 2017

  公益社団法人 日本生体医工学会

キーワード

• retinal prosthesis
• artificial retina
• brain–machine interface
• safety evaluation
• animal testing

詳細情報

• CRID: 1390282680480641920
• NII論文ID: 130005395534
• DOI: 10.14326/abe.6.8
• ISSN: 21875219
• Web Site: https://www.jstage.jst.go.jp/article/abe/6/0/6_6_8/_pdf
• Web Site: https://search.jamas.or.jp/link/ui/2018364070
• 本文言語コード: en
• データソース種別:
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