BACKGROUND: Suprachoroidal-transretinal stimulation (STS) can potentially restore vision. This study investigated the spatial characteristics of cortical electrical evoked potentials (EEPs) elicited by STS. METHODS: A 4 × 4 thin-film platinum microelectrode stimulating array (200 μm electrode diameter and 400 μm center-to-center distance) was fabricated by a micro-electro-mechanical systems (MEMS) techniques and implanted into the suprachoroidal space of albino rabbits. RESULTS: The current threshold to elicit reliable EEPs by a single electrode was 41.6 ± 12.6 μA, corresponding to a 66.2 ± 20.1 μC · cm(-2) charge density per phase, which was lower than the reported safety limits. Spatially differentiated cortical responses could be evoked by STS through different rows or columns of electrical stimulation; furthermore, shifts in the location of the maximum cortical activities were consistent with cortical visuotopic maps; increasing the number of simultaneously stimulating electrodes increased the response amplitudes of EEPs and expanded the spatial spread as well. In addition, long-term implantation and electrical stimulation of the MEMS electrode array in suprachoroidal space are necessary to evaluate systematically the safety and biocompatibility of this approach. CONCLUSIONS: This study indicates that the STS approach by a MEMS-based platinum electrode array is a feasible alternative for visual restoration, and relatively high spatial discrimination may be achieved.
BACKGROUND:Suprachoroidal-transretinal stimulation (STS) can potentially restore vision. This study investigated the spatial characteristics of cortical electrical evoked potentials (EEPs) elicited by STS. METHODS: A 4 × 4 thin-film platinum microelectrode stimulating array (200 μm electrode diameter and 400 μm center-to-center distance) was fabricated by a micro-electro-mechanical systems (MEMS) techniques and implanted into the suprachoroidal space of albino rabbits. RESULTS: The current threshold to elicit reliable EEPs by a single electrode was 41.6 ± 12.6 μA, corresponding to a 66.2 ± 20.1 μC · cm(-2) charge density per phase, which was lower than the reported safety limits. Spatially differentiated cortical responses could be evoked by STS through different rows or columns of electrical stimulation; furthermore, shifts in the location of the maximum cortical activities were consistent with cortical visuotopic maps; increasing the number of simultaneously stimulating electrodes increased the response amplitudes of EEPs and expanded the spatial spread as well. In addition, long-term implantation and electrical stimulation of the MEMS electrode array in suprachoroidal space are necessary to evaluate systematically the safety and biocompatibility of this approach. CONCLUSIONS: This study indicates that the STS approach by a MEMS-based platinum electrode array is a feasible alternative for visual restoration, and relatively high spatial discrimination may be achieved.
Authors: Mohit N Shivdasani; Chi D Luu; Rosemary Cicione; James B Fallon; Penny J Allen; James Leuenberger; Gregg J Suaning; Nigel H Lovell; Robert K Shepherd; Chris E Williams Journal: J Neural Eng Date: 2010-05-18 Impact factor: 5.379
Authors: Mohit N Shivdasani; James B Fallon; Chi D Luu; Rosemary Cicione; Penny J Allen; John W Morley; Chris E Williams Journal: Invest Ophthalmol Vis Sci Date: 2012-09-19 Impact factor: 4.799
Authors: Yasuyuki Yamauchi; Luisa M Franco; Douglas J Jackson; John F Naber; R Ofer Ziv; Joseph F Rizzo; Henry J Kaplan; Volker Enzmann Journal: J Neural Eng Date: 2005-02-22 Impact factor: 5.379
Authors: Brandon Bosse; Samir Damle; Abraham Akinin; Yi Jing; Dirk-Uwe Bartsch; Lingyun Cheng; Nicholas Oesch; Yu-Hwa Lo; Gert Cauwenberghs; William R Freeman Journal: Invest Ophthalmol Vis Sci Date: 2018-12-03 Impact factor: 4.799