In vivo Biocompatibility and Stability of Polyimide Microelectrode Array for Retinal Stimulation

Abstract

Abstract: : Purpose: To investigate the long-term biocompatibility and stability of strip-shaped polyimide microelectrode array, implantation was performed into the rabbit eye and the regular follow-up was done. Methods: To minimize the damage during ophthalmic surgery and to get better contact to the retina, flexible polyimide, which can be fabricated based on semiconductor manufacturing, is selected as the substrate material. Strip-shaped electrode array was introduced into subretinal space via transscleral approach from the limbus toward the posterior pole of the rabbit eye. Stimulation site was located near the visual streak of posterior pole and the connection site was kept on the external surface of the sclera. In one eye, extraocular connection site was integrated with small polychlorinated biphenyl (PCB) board before the implantation for easy connection to the stimulation system. Extraocular part of the microelectrode array was covered with Tenon’s capsule and conjunctiva. PCB board was fixed on the sclera by non-absorbable suture. Regular ophthalmoscopic examination and electroretinography were done. Results: There was no evidence of movement of the subretinal polyimide microelectrode array. The sign of hemorrhage or inflammation was not found during the follow-up period. In spite of the relatively large size of the PCB-integrated array, it was kept in situ and the PCB board was well encapsulated by the connective tissues under the Tenon’s capsule. Electroretinogram showed no difference between the operated and the fellow eye. Conclusions: The transscleral approach into the subretinal space can be safely done in a rabbit eye and the strip-shaped polyimide microelectrode array may be used in acute and chronic experiments for retinal stimulation.

Keywords: retina • transplantation • animal model