Transretinal Electrical Stimulation with a Suprachoroidal Multichannel Electrode in Rabbit Eyes

Sakaguchi, Hirokazu; Fujikado, Takashi; Fang, Xiaoyun; Kanda, Hiroyuki; Osanai, Makoto; Nakauchi, Kazuaki; Ikuno, Yasushi; Kamei, Motohiro; Yagi, T.; Nishimura, S.; Ohji, Masahito; Tano, Yasuo

doi:10.1007/s10384-004-0055-1

Cited by 86 publications

(66 citation statements)

References 18 publications

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“…This value is comparable to the findings of Sakaguchi et al (42 lC cm À2 ) using a 500 ls phase and a 100 lm electrode 45 ; Nakauchi et al 46 (56 lC cm À2 ), with a 180 lm electrode and 500 ls phase time; and Zhou et al (48.64 lC cm À2 ) using a 1 ms phase time and a 300 lm electrode. 23 Monopolar and hexapolar (128.5 6 11.4 lC cm À2 ) results are within the range of studies by Wong et al 31 (184 lC cm…”

Section: Discussion Cortical Thresholdssupporting

confidence: 79%

Current Steering in Retinal Stimulation via a Quasimonopolar Stimulation Paradigm

Matteucci

Chen

Tsai

et al. 2013

Invest. Ophthalmol. Vis. Sci.

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PURPOSE. Research to restore some degree of vision to patients suffering from retinal degeneration is becoming increasingly more promising. Several groups have chosen electrical stimulation of the remaining network of a degenerate retina as a means to generate discrete light percepts (phosphenes). Approaches vary significantly, with the greatest difference being the location of the stimulating electrode itself.METHODS. Suprachoroidal positioning offers excellent mechanical stability and surgical simplicity; however, at the cost of activation thresholds and focused stimulation due to the distance from the electrodes to the target neurons. Past studies proposed a hexapolar electrode configuration to focus the cortical activation and minimize cross-talk between electrodes during concurrent stimulation. The high impedance nature of the choroid and pigment epithelium, however, cause current to shunt between the stimulating and return electrodes, resulting in even higher activation thresholds. In our study, we analyzed the effect of stimulating the feline retina using a quasimonopolar stimulation by simultaneously stimulating a hexapolar and distant monopolar return configurations. RESULTS.Results of in vivo studies showed that quasimonopolar stimulation can be used to maintain the activation containment properties of hexapolar stimulation, while lowering the activation threshold to values almost equivalent to those of monopolar stimulation.CONCLUSIONS. The optimal stimulus was found to be composed of a subthreshold monopolar stimulus combined with a suprathreshold hexapolar stimulation. This resulted in a decrease of activation threshold of 60% with respect to hexapolar alone, but with no discernible deleterious effect on the charge containment of a pure hexapolar stimulation.

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Section: Discussion Cortical Thresholdssupporting

confidence: 79%

Current Steering in Retinal Stimulation via a Quasimonopolar Stimulation Paradigm

Matteucci

Chen

Tsai

et al. 2013

Invest. Ophthalmol. Vis. Sci.

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“…The species involved include rats (n=6) [26,29,76,80,81,96], rabbits (n=14) [33,36,42,72,73,90,94,95,102,103,105,106,116,121], cats (n=18) [18, 19, 21-23, 30, 32, 43, 78, 79, 82, 93, 98, 99, 101, 114, 117, 120], dogs (n=4) [16,39,40,66], sheep (n=1) [51] and pigs/minipigs (n=9) [34,42,49,59,69,91,92,100,102]. Two papers [16,26] which involved three animal species do not figure in Table 2 due to lack of space, but are discussed in the review.…”

Section: Resultsmentioning

confidence: 99%

A review of in vivo animal studies in retinal prosthesis research

Bertschinger¹,

Beknazar²,

Silva

et al. 2008

Graefes Arch Clin Exp Ophthalmol

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Background The development of a functional retinal prosthesis for acquired blindness is a great challenge. Rapid progress in the field over the last 15 years would not have been possible without extensive animal experimentation pertaining to device design and fabrication, biocompatibility, stimulation parameters and functional responses. This paper presents an overview of in vivo animal research related to retinal prosthetics, and aims to summarize the relevant studies. Methods A Pubmed search of the English language literature was performed. The key search terms were: retinal implant, retinal prosthesis, artificial vision, rat, rabbit, cat, dog, sheep, pig, minipig. In addition a manual search was performed based on references quoted in the articles retrieved through Pubmed. Results We identified 50 articles relevant to in vivo animal experimentation directly related to the development of a retinal implant. The highest number of publications related to the cat (n=18). Conclusion The contribution of animal models to the development of retinal prosthetic devices has been enormous, and has led to human feasibility studies. Grey areas remain regarding long-term tissue-implant interactions, biomaterials, prosthesis design and neural adaptation. Animals will continue to play a key role in this rapidly evolving field.

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“…(4)(5)(6) In subretinal stimulation, the electrode array is placed in the subretinal space. In epiretinal stimulation, the electrode array is attached to the vitreous side of the retina.…”

Section: Introductionmentioning

confidence: 99%

Clinical Trial of Chronic Implantation of Suprachoroidal-Transretinal Stimulation System for Retinal Prosthesis

2012

Sensors and Materials

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Retinal prosthesis is an implantable medical device to reconstruct the sense of sight for blind individuals. We have been developing a new type of retinal prosthesis called suprachoroidal-transretinal stimulation (STS), whereby an electrode array is not attached to the retina directly. To evaluate the feasibility and safety of the retinal prosthesis using STS, a clinical trial was performed. We have developed an internal device for chronic implantation. It consists of a 49-channel electrode array that has 9 active electrodes. The retinal prosthesis was implanted in two patients with advanced retinitis pigmentosa (RP). Follow-up periods after implantation were five (Pt 1) and seven (Pt 2) weeks. No significant adverse event was observed in either patient after the surgical procedures. A functional test revealed that the detection or discrimination of objects was possible using the device, and a pulse frequency of around 20 Hz is the most effective in evoking phosphene. These clinical examinations showed that the retinal prosthesis with the STS system is safe and feasible for artificial vision.

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Transretinal Electrical Stimulation with a Suprachoroidal Multichannel Electrode in Rabbit Eyes

Abstract: Transretinal electrical stimulation from the suprachoroidal space could elicit EEP, suggesting that this approach may be useful for a retinal prosthesis system.

Cited by 86 publications

References 18 publications

Current Steering in Retinal Stimulation via a Quasimonopolar Stimulation Paradigm

Current Steering in Retinal Stimulation via a Quasimonopolar Stimulation Paradigm

A review of in vivo animal studies in retinal prosthesis research

Clinical Trial of Chronic Implantation of Suprachoroidal-Transretinal Stimulation System for Retinal Prosthesis

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