In Vivo Experiment With 3D Microelectrode Array on a Flexible Substrate for Retinal Prosthesis

Abstract

Purpose: : To evaluate the feasibility of 3D microelectrode array (MEA) for retinal prostheses.

Methods: : Polyimide-based 3D MEA had 171 arrowhead-shaped gold electrodes, and the size of each electrode is 15 x 15 to 125 x 125 µm in the base area, and 50 to 125 µm in the height. Electrodes are protruded on the surface of MEA, aligned in concave or convex style. MEA was implanted in the suprachoroidal space of the rabbit eye through scleral tunnel incision with the aid of polyimide guide to protect protruded electrodes during surgery. Electrically evoked cortical potential (EECP) at visual cortex was measured under electrical retinal stimulation and spectral domain optical coherence tomography (OCT, Cirrus^TM) was done serially for 1 month to identify in vivo stability and biocompatibility of the array.

Results: : On EECP, the peak amplitude was 100 to 159 µV with the implicit time of 10 to 13 ms, and the peak amplitude was proportional to the strength of the stimulation current. OCT revealed that 3D MEA was well-preserved in the suprachoroidal space without adjacent tissue damage or complication during follow-up period.

Conclusions: : In vivo experiment showed that proposed 3D MEA could be used for the effective and safe electrical stimulation of the retina for the visual prosthesis.

Keywords: retina • retinal degenerations: hereditary • transplantation