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Rosemary Cicione, Mohit N. Shivdasani, James B. Fallon, Chi D. Luu, Penny J. Allen, Graeme Rathbone, Chris E. Williams; Efficacy of Electrode Return Configuration in a Suprachoroidal Retinal Prosthesis. Invest. Ophthalmol. Vis. Sci. 2011;52(14):4961.
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© ARVO (1962-2015); The Authors (2016-present)
To determine the effect of electrode return configuration on charge threshold and spatial selectivity in suprachoroidal electrical stimulation of the retina.
A flexible polyimide substrate electrode array was inserted into the suprachoroidal space of normally-sighted, anesthetized cats (n=5). Individual electrodes on the array were electrically stimulated in three return configurations: monopolar (MP, return electrode in vitreous humour), common ground (CG, all remaining electrodes used as return) and hexagonal (HX, six electrodes surrounding active used as return) while recording multiunit activity from the visual cortex. For each retinal electrode stimulated, a best cortical site, defined as the recording site in the visual cortex with the lowest threshold was found. Spike rate at suprathreshold charge levels (normalized to that of the best cortical site) was determined across the cortex in order to ascertain the spatial selectivity of each return configuration.
Charge threshold of MP stimulation was significantly lower than that of both CG and HX configurations (Fig. 1A, *, p<0.05). There was no significant difference in spatial selectivity among the three return configurations.
MP electrode return stimulation is the most charge efficient in a suprachoroidal retinal prosthesis. Electrode return configuration has little influence on spatial selectivity.
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