Electronic retinal prostheses seek to restore sight in patients with retinal degeneration by delivering pulsed
electric currents to retinal neurons via an array of microelectrodes. Most implants use inductive or optical transmission
of information and power to an intraocular receiver, with decoded signals subsequently distributed to retinal electrodes
through an intraocular cable. Surgical complexity could be minimized by an "integrated" prosthesis, in which both
power and data are delivered directly to the stimulating array without any discrete components or cables. We present
here an integrated retinal prosthesis system based on a photodiode array implant. Video frames are processed and
imaged onto the retinal implant by a video goggle projection system operating at near-infrared wavelengths (~ 900 nm).
Photodiodes convert light into pulsed electric current, with charge injection maximized by specially optimized series
Prostheses of three different pixel densities (16 pix/mm2, 64 pix/mm2, and 256 pix/mm2) have been designed,
simulated, and prototyped. Retinal tissue response to subretinal implants made of various materials has been investigated
in RCS rats. The resulting prosthesis can provide sufficient charge injection for high resolution retinal stimulation
without the need for implantation of any bulky discrete elements such as coils or tethers. In addition, since every pixel
functions independently, pixel arrays may be placed separately in the subretinal space, providing visual stimulation to a
larger field of view.