Intraocular Retinal Prosthesis

James D. Weiland, PhD,
Keck School of Medicine-Ophthalmology,
University of Southern California

A retinal prosthesis has the potential to treat blinding diseases of the outer retina, such as age-related macular degeneration and retinitis pigmentosa. An on-going clinical trial is evaluating a low-resolution device while technologies to support higher resolution implants are under development. A prototype epiretinal prosthesis was implanted in six subjects with bare or no light perception due to retinitis pigmentosa. The FDA granted an IDE and USC-IRB approved the study protocol. Subjects were screened using visual psychophysics, electrophysiology, ophthalmic photography, and scanning laser ophthalmoscopy. Implants consist of an extraocular microelectronic device and an intraocular electrode array, connected by a multiwire cable. The electrode array is a 4×4 grid of platinum electrodes embedded in silicone rubber. Electrodes are wirelessly activated using an external system. The external system is controlled via a computer interface or a head mounted video camera. To date, 6 subjects have been implanted for 13-41 months. Performance using the head mounted video camera suggests that patients are capable of interpreting patterned electrical stimulation. Using data generated by the clinical trial, considerable progress has been made towards a higher resolution device. An image processing system has been realized that is capable of real-time implementation of image decimation and filtering (for example, edge detection). Application specific integrated circuits (ASICs) have been designed and tested to demonstrate closed loop power control and efficient microstimulation. A novel packaging process has been developed that is capable of simultaneously forming a receiver coil, interconnects, and stimulating electrodes. The high-resolution system is targeting 1000 electrodes, which simulations predict can restore face recognition and mobility to blind individuals.
James Weiland received his B.S. from the University of Michigan in 1988. After 4 years in industry with Pratt & Whitney Aircraft Engines, he returned to Michigan for graduate school, earning degrees in Biomedical Engineering (M.S. 1993, Ph.D. 1997) and Electrical Engineering (M.S. 1995). He joined the Wilmer Ophthalmological Institute at Johns Hopkins University in 1997 as a postdoctoral fellow and, in 1999, was appointed an assistant professor of ophthalmology at Johns Hopkins. Dr. Weiland joined the Doheny Eye Institute in 2001. Currently, Dr. Weiland is the Director of the Intraocular Retinal Prosthesis Laboratory and an Assistant Professor of Ophthalmology, Keck School of Medicine, University of Southern California, and an Assistant Professor of Biomedical Engineering, University of Southern California. Dr. Weiland's research interests include retinal prostheses, neural prostheses, electrode technology, visual evoked responses, and implantable electrical systems. He is a member of the IEEE EMBS, the Biomedical Engineering Society, and the Association for Research in Vision and Ophthalmology.