Interdisciplinary Initiatives Program Round 4 – 2008

Daniel Palanker, Opthalmology
Stephen Baccus, Neurobiology
Peter Peumans, no longer at Stanford

Retinitis pigmentosa (RP) and end-stage macular degeneration (AMD) lead to blindness due to progressive loss of photoreceptors, the light sensing cells of the retina. Some visual function can be restored by stimulating the remaining retinal neurons using a retinal prosthetic that encodes the visual information into electrical signals. This project brings together a unique combination of engineers, neurobiologists, and ophthalmologists to develop and evaluate a high-resolution retinal prosthetic system designed specifically to achieve functional levels of vision. In this system processed images of the visual scene are projected by pulsed infrared light onto a subretinally placed microphotodiode array. Photovoltaic pixels in the array convert pulsed light into biphasic pulses of electric current that directly stimulate retinal neurons. In this approach hundreds or thousands of pixels in the implant can be activated simultaneously and independently, providing high resolution stimulation, and maintaining the natural link between eye movements and image perception. The modular implant design and lack of wires greatly simplifies surgical procedure and allows expansion of the stimulated field. Such a versatile system could address the divergent needs of RP and AMD patients.