2008 Volume 5 Issue 15 Pages 574-580
A visual prosthesis is an artificial sensory organ that transmits visual information to a blind person by electrically stimulating residual neurons in the visual nervous system. Such a system requires a large number of stimulating electrodes: It is technically difficult to connect a stimulator placed behind the ear to each of the stimulating electrodes over any significant distance with high reliability. We propose a visual prosthesis containing a multiplexer that is separately placed from the stimulator unit. The array of stimulating electrodes is connected to the stimulation unit through a multiplexer. The stimulating electrodes and multiplexer are placed onto the suprachoroidal space. The stimulation unit consists of a metal case and a coil and is implanted in the postauricular region of the cranium. The multiplexer and the stimulator unit are connected by a cable composed of six wires. Incorporating the multiplexer enables us to control of a large number of electrodes using a small number of conductors in the cable. We have developed a system with 100 electrodes which is powered and controlled wirelessly. Then we have confirmed that the proposed system functions successfully both in vitro and in vivo.
