Device Stimulating Visual Cortex of Brain Promises Independence for the Totally Blind
New York, NY, January 18, 2000 - A biomedical engineering team today announced development of an artificial vision system providing independent mobility to blind people. The system, reflecting more than 30 years in development work by the Dobelle Institute in New York City and its affiliates on Long Island and in Switzerland, enables a totally blind person to achieve visual acuity of about 20/400, in a narrow visual "tunnel." The "Dobelle Eye," as described in the current issue of the ASAIO Journal (the journal of American Society of Artificial Internal Organs) and in companion commentaries in Nature and Lancet, consists of a sub-miniature television camera and an ultrasonic distance sensor, both of which are mounted on a pair of eyeglasses. The sensors connect through a cable to a miniature computer, which is worn in a pack on a person's belt. After processing the video and distance signals, the computer uses sophisticated computer-imaging technology, including edge-detection algorithms to simplify the image eliminating "noise." The computer then triggers a second microcomputer that transmits pulses to an array of 68 platinum electrodes implanted on the surface of the brain's visual cortex. Bringing wires through the skin for two decades without discomfort or infection is one of many independent inventions that has made the new visual prosthesis possible.
When stimulated, each electrode produces one to four closely spaced phosphenes, which have been described as resembling "stars in the sky." This white phosphene on a black background "map" is roughly eight inches by two inches at arms length.
The patient in the study reported in ASAIO Journal is a 62-year-old male who was totally blinded by trauma when he was 36 years old. After learning to use the system and "read" the display, the patient is now able to read two inch tall letters at a distance of five feet, representing a visual acuity of about 20/400. Although the relatively small electrode array produces tunnel vision, the patient is also able to navigate in unfamiliar environments including the New York City subway system. By replacing the sub-miniature television camera with a special electronic interface, the patient is also learning to "watch" television, use a computer, and gain access to the Internet.
The computer package employed in the initial system was the size of a large bookcase and weighed several thousand pounds. After six generations of improvement over the last 21 years, the external electronics package has now been miniaturized so it is about the size of a dictionary and weighs approximately ten pounds, including batteries.
Dr. Dobelle's first human experiments in this artificial vision project took place beginning in 1970 and involved cortical stimulation of 37 sighted volunteers undergoing surgery on the occipital lobe under local anesthesia to remove tumors and other lesions. Three blind volunteers were then temporarily implanted with electrode arrays to stimulate the visual cortex. Subsequent experiments involved four blind volunteers who were implanted with permanent electrode arrays employing percutaneous connecting pedestals. The Dobelle system's electrodes and connecting pedestal were surgically implanted in two blind volunteer's brains in 1978 at the Columbia-Presbyterian Medical Center in New York City. Both have retained their implants and one is the subject of the study reported in the ASAIO Journal.
Dr. Dobelle said that the new artificial vision systems are expected to be made available, on a limited commercial basis, starting later this year.
The Dobelle Institute and its commercial affiliates in Long Island, NY and Zurich, Switzerland constitute one of the world's most sophisticated organizations for education, research, development, manufacturing and clinical implementation of medical devices. Over the last 30 years, the Dobelle Institute has been responsible for the design, manufacture and distribution of other neurological "pacemakers" to control breathing, intractable pain and the urogenital system of about 15,000 patients in more than 40 countries. These clinical systems have gained full regulatory and reimbursement approval from the FDA, Medicare and analogous foreign agencies.
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