Development of a minimally invasive retinal implant system

Purpose. It was the aim of this project to develop a minimally invasive prosthetic retinal implant system for the rehabilitation of blind patients suffering from distal retinal degenerations. For this purpose, encoded image information will be transferred to surviving retinal neurons by electrical stimulation applied via intraretinal microelectrodes. Methods. The technological concept was generated in a feasibility study of alternative approaches to minimally invasive retinal prostheses. Then two series of test implants were fabricated and applied in different in vitro- and in vivo- studies before a long-term implantation trial was initiated. Results. The conceptual design process was resulting in a system with stimulating microelectrodes penetrating the sclera and choroid ab externo, and with all other implant components in episcleral position. Microelectrode penetration and surgical application techniques were successfully tested in several series of experiments. Finally, a long-term application of test devices was successfully initiated. Conclusion. Results so far demonstrate the conceptual feasibility, easy-to-perform surgical application, and long-term biocompatibility of the newly designed minimally invasive retinal implant system.