A miniature camera connected by computer to electrodes implanted in the brain has enabled a blind man to see, said a team of biomedical engineers at the Dobell Institute in New York.
The device, which has been in development for more than 30 years, produces a display of white dots against a black background which the patient learns to "read", producing a visual acuity of about 20/400, in a narrow visual tunnel, the institute said yesterday in a statement.
"Our progress represents the work of more than 300 scientists, engineers and physicians who contributed to various aspects of the project," said the institute's founder, Mr William Dobell.
Implanted in a 62-year-old man left blind by an accident 26 years ago, the device, called the "Dobell Eye", allows him to read 5cm tall letters at a distance of 160cm, the statement said.
Despite the limited field of vision, the patient is able to travel unassisted in unfamiliar environments, "including the New York city subway system". Coupled with a special electronic interface, he is also learning to "watch" television, use a computer and gain access to the Internet.
The revolutionary device consists of a sub-miniature television camera and an ultrasonic distance sensor, both of which are mounted on a pair of glasses. The sensors are connected by cable to a miniature computer worn in a pack on a belt.
The computer is about the size of a dictionary and weighs about 4kg (10lb).
The computer simplifies the video and distance signals and triggers a second microcomputer that transmits pulses to an array of 68 platinum electrodes implanted in the surface of the brain's visual cortex.
"With further refinements, including larger arrays of electrodes and more powerful computers," said Dr Dobell, "the system is expected to provide a `cure' for most types of pediatric and adult blindness.
"Brains of sighted people respond to stimulation like those of blind people, so the system may also be useful for people with very low vision," he added.