gms | German Medical Science

Purpose: Electrical stimulation of retina with microelectrode array (MEA) has been suggested as a possible method for retinal prosthesis. In our research, stimulation of retina was achieved by epiretinal or suprachoroidal application of three-dimensional MEA. For the epiretinal fixation of the MEA, PMMA microtack with grating was developed. To evaluate the tonotopicity of the retina onto the visual cortex on electrical retinal stimulation, multiple depth electrodes were used and the electrically evoked cortical potential (EEP) was recorded.

Methods: We designed PMMA(poly-methyl metharcylate) retinal tacks with barb-shaped scale bar which could act as an index in measuring the penetration depth. Using OCT, the scale bar was checked after insertion with 3D epiretinal electrode onto the rabbit’s retina. The implanted electrode with retinal tack was harvested to confirm the biocompatibility and durability. And multichannel EEP’s were recorded with 16 channel cortical electrode array in the rabbit’s visual cortex using multichannel electrophysiological workstation after insertion of polyimide based MEA with 3D electrode into the suprachoroidal space.

Results: The scale bars of the retinal tack could be confirmed on Cirrus OCT evaluation. Through histologic examination, no inflammatory infiltrates was revealed. And 16 channel EEP recording provided two dimensional information of cortical responses on electrical retinal stimulation. We could confirm the different two dimensional patterns of EEP by electrical stimulation of different areas of retina.

Conclusions: The PMMA retinal tack was suitable to measure the penetration depth of an inserted 3D epiretinal electrode. And multichannel EEP recording could be used in topological evaluation of the visual cortical responses.

This lecture is available as video recording (Attachment 1 [Attach. 1]).