Developments on the Boston 256-channel retinal implant

A hermetic neurostimulator is being developed to restore functional sight to the blind. The latest developments are presented on the Boston 256-channel retinal prosthesis. The device includes a hermetic package made of titanium and alumina, containing an integrated circuit chip with 256 independently addressable current drivers. The prosthesis attaches to the outside scleral wall of the eye and electrically drives a microfabricated thin-film polyimide array of sputtered iridium oxide electrodes. This array is implanted in the subretinal space via a flap in the sclera. The implanted device receives power and stimulation data wirelessly via inductively coupled coils. A circuit to prevent residual electrode voltage and improve safety is being designed for incorporation into future devices. The components of our prosthesis have been tested, and we plan to implant the 256-channel device in animals this year.