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A retinal prosthesis was permanently implanted in the eye of a completely blind test subject. This report details the results from the first 10 weeks of testing with the implant subject. The implanted device included an extraocular case to hold electronics, an intraocular electrode array (platinum disks, 4 x 4 arrangement) designed to interface with the(More)
Loss of photoreceptor cells is one of the major causes of blindness. Several groups are exploring the functional replacement of photoreceptors by a retinal prosthesis. The goal of this study was to simulate the vision levels that recipients of retinal prostheses with 4 x 4, 6 x 10, and 16 x 16 electrode arrays may experience, and to test the functionality(More)
This study defines and compares the topologies of the visual evoked potentials to various stimuli such as pattern onset/offset, pattern reversal, pattern motion and high frequency luminance flicker. The responses recorded from 24 occipital derivations were examined using a three sphere conductance model to represent the head, with the assumption that(More)
OBJECTIVE To evaluate the feasibility of bypassing damaged photoreceptors and electrically stimulating the remaining viable retinal layers to provide limited visual input to patients who are blind because of severe photoreceptor degeneration. METHODS In the operating room with the patient under local anesthesia, focal electrical stimulation of the retinal(More)
Experiments were conducted to study if electrical stimulation of the retinal surface can elicit visual sensation in individuals blind from end-stage retinitis pigmentosa (RP) or age-related macular degeneration (AMD). Under local anesthesia, different stimulating electrodes were inserted through the eyewall and positioned over the surface of the retina.(More)
Most of current concepts for a visual prosthesis are based on neuronal electrical stimulation at different locations along the visual pathways within the central nervous system. The different designs of visual prostheses are named according to their locations (i.e., cortical, optic nerve, subretinal, and epiretinal). Visual loss caused by outer retinal(More)
PURPOSE To evaluate a model of simulated pixelized prosthetic vision using noncontiguous circular phosphenes, to test the effects of phosphene and grid parameters on facial recognition. METHODS A video headset was used to view a reference set of four faces, followed by a partially averted image of one of those faces viewed through a square pixelizing grid(More)
Vision restoration through retinal, optic nerve, and cortical implants is no longer just the stuff of fantasy. The design and development of visual prostheses rapidly move from the engineering phase toward preclinical and clinical trials, yet the benchmarks to determine their efficacy in blind research subjects have received very little attention, and(More)
PURPOSE To investigate the feasibility of adequate reading by recipients of future prosthetic visual implants through simulation in sighted observers. METHODS Four normally sighted subjects used a video headset to view short-story segments at a sixth grade reading level, presented in 6- to 11-word paragraphs through a pixelizing grid defined by five(More)
Wayfinding is an important activity that can be performed with limited visual resources, and thus may be an important application of early visual prostheses. In a pair of experiments we explored minimal visual resolution requirements of a simulated retinal electrode array for mobility in real and virtual environments, experienced by normally sighted(More)