U.S. has its first bionic eye.
The Argus II works by substituting a small array of
electrodes for the light-sensing cells that normally react to light by sending
an electric signal toward the back of the retina. Those signals are relayed to
the optic nerve behind the eye, and travel back along the nerve to the brain.
In people with the genetic disease Retinitis pigmentosa, which affects about
100,000 people in the U.S. today, those light-sensing cells gradually stop
working, resulting in total blindness.
In addition to the electrode array, which is implanted in
the retina at the back of the eye, the Argus II system consists of a small
video camera attached to a pair of eyeglasses and a visual processor the user
carries around their waist. Data from the video camera is sent to the visual
processor and then back to the glasses, where it is transmitted wirelessly to
the embedded electrodes.
The system works for people with RP because the disease affects the light-sensing cells in the retina, but leaves the rest of the visual system--including the optic nerve, which carries visual signals from the retina to the brain--intact. The electrode array acts as a substitute for the eye's photoreceptors by directly stimulating the retina's remaining cells, which pass the signal on to the optic nerve.Of course, an array of 60 electrodes cannot restore high-resolution vision--it's like watching TV on a screen with just 60 pixels--but it can supply enough information to allow people to move around without aid.
