JAMES D. WEILAND
PHD, Professor of Ophthalmology and Biomedical Engineering, University of Southern California US
Retinal prosthesis for the blind
JAMES D. WEILAND
Novel science and technology are revolutionizing the field of ophthalmology and making possible restoration of vision in previously incurable diseases. This presentation will review three approaches that are at different stages of development: bioelectronic retinal prostheses, stem-cell therapy for age-related macular degeneration (AMD), and wearable computer vision systems. Bioelectronic retinal prostheses have progressed from laboratory and early clinical experiments, to medical devices approved for sale by the FDA and European Union. The clinical trials have shown that individuals who have at best light perception vision, can use spatial information from the retinal prosthesis to detect motion, locate objects, and read letters. Improvements in navigation and mobility have been noted. To treat AMD, which is characterized by a loss of retinal pigment epithelial (RPE) cells, a novel stem cell treatment uses RPE cells derived from stem cells which are then seeded onto a synthetic membrane. The implanted scaffold of RPE cells will function to support and replenish photoreceptors of the retina, which may help restore and prevent vision loss in patients with AMD. Safety and efficacy of the implant was confirmed based on the animal studies. As well, results indicated that the stem cell therapy successfully decreased the progression of retinal degeneration in rats. This therapy will be used to treat patients in the upcoming phase 1 human clinical trial. A third approach to treating blindness involves a prototype computer vision system, aiding in navigation and object localization. A complete processing algorithm has been constructed that allows a user to instruct the wearable camera and computer system to find a particular object. Once the object is located, the wearable computer system provides verbal and/or tactile cues to guide the user to the object of interest. Tests show that blind volunteers are able to follow these cues to complete navigation tasks and reach-and-grasp tasks. Brain imaging of the central visual pathways will be a key technique for evaluating the long-term effects of these therapies, since modifications in the visual input will result in.
Retinitis pigmentosa (RP) and age-related macula degeneration (AMD) lead to the degeneration of the light sensitive cells of the eye (photoreceptors), resulting in a significant visual deficit for the afflicted individual. In a retina affected by RP or AMD, the photoreceptors are absent, but other cells of the retina remain present in large numbers. Current clinical trials are investigating the feasibility of replacing the function of the photoreceptors with an electronic device that will electrically stimulate the remaining cells of the retina to generate visual perceptions. In tests with human volunteers with little or no light perception, we have used a prototype retinal prosthesis with a limited number of stimulating electrodes to create the perception of discrete spots of light. Subjects were able to distinguish basic shapes, to detect motion, navigate towards a target, and read letters. Based on these encouraging results, two devices have received regulatory approval. Our current research involves investigating methods to optimize the visual information that can be provided by a retinal implants.
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 was appointed assistant professor at the Doheny Eye Institute-University of Southern California in 2001. Currently, Dr. Weiland is a Professor of Ophthalmology and Biomedical Engineering, University of Southern California. He is Deputy Director of the Biomimetic Microelectronic Systems Engineering Research Center. Dr. Weiland’s research interests include retinal prostheses, neural prostheses, electrode technology, visual evoked responses, implantable electrical systems, and wearable visual aids for the blind. He is a Fellow of the American Institute of Medical and Biological Engineering and a Senior Member of the IEEE. He is a member of EMBS, Sigma Xi, and the Association for Research in Vision and Ophthalmology