Electronic eye for blind man
had the wires entering his brain for 21 years
The first useful artificial eye is now helping a blind man walk
safely around and read large letters, researchers said on Monday.
62-year-old man, identified only as Jerry, demonstrated that he was able to
collect a black hat off a white wall, then locate a mannequin and place the
hat on its head.
blinded by an accident at the age of 36, does not see an image but up to 100
specks of light that appear and disappear as his field of vision shifts. The
specks show up the edges of objects. The constellation of dots, called
phosphenes, has been likened to stars that glitter and fade behind passing
"He can do
remarkably well," said Dr William Dobelle, chairman of the Dobelle
medical device company that has developed the system.
Normann, an artificial vision expert at the University of Utah, stressed
that the device was "a very limited navigational aid, and a far cry from the
visual experience that normal people enjoy".
said the work suggested that even limited signals to the brain would let
blind people do relatively complicated visual tasks.
Heetderks, director of a US National Institutes of Health programme to
develop electronic implants that work with the brain, believes an implant
that helps blind people navigate would be a major step forward.
Dobelle provides additional details on his methodology that establishes this
result, we may be there," Dr Heetderks said. The device and its performance
are described in the January/February issue of the American Society of
Artificial Internal Organs Journal.
artificial vision system works by taking an image from a miniature
television camera and distance
information from an ultrasound sensor, each of
which is mounted on one lens of a pair of sunglasses.
These signals are processed by a five-kilogram (10 pounds) portable computer
and then a new signal is sent to 68 platinum electrodes implanted in the
person's brain. The electrodes are on the surface of the brain's visual
cortex and stimulate the person to 'see' the phosphenes.
recognised five-centimetre-tall (two inches) letters from 1.5 metres (five
feet) away, said Dr Dobelle. The device provides "tunnel vision", with the
field of view being equivalent to a card 20 cm tall by five centimetres wide
(eight by two inches) held at arm's length.
Dr Dobelle said that Jerry had been able to navigate in unfamiliar
environments, including the
New York City
subway system. He added that , with a special electronic interface taking
the place of the camera, Jerry was also learning to use a computer.
with another volunteer, had the electrodes implanted in his brain in 1978.
Since then the computer used has shrunk in size and the software improved.
One aspect of
future development will focus on how best to provide depth perception -
during the demonstration Jerry had to walk cautiously as he approached the
mannequin and the wall, holding out an arm to prevent collisions.
said a version of the device should go on sale outside the US later this