Profoundly blind people could get their best shot yet of restored vision with a more advanced "bionic eye", researchers have announced.
Trials of the new retinal prosthesis will begin shortly, following the success of a prototype that has enabled six blind people to see again.
Within a few weeks all could detect light, identify objects and even perceive motion again. For one patient, this was the first time he had seen anything in half a century, after his sight was destroyed by retinitis pigmentosa, a virus that attacks retinal cells.
"We hoped they might get some sense of light and dark, but it's really amazing how much they can see - how the brain is able to fill in the gaps," says Mark Humayun, who carried out the implant surgery and developed the device with colleagues at Doheny Eye Institute at the University of Southern California in the US.
For the technique to work, the patient must still have some functioning ganglion cells - nerve cells that transmit visual information from the retinal cells to the optic nerve - as well as a fully-functioning optic nerve. A tiny electronic pad is placed onto the retina of one eye, so that the electrodes are in direct contact with the ganglion cells. Each of the devices' 16 electrodes can stimulate 20 to 30 cells.
The user wears a pair of glasses that contain a miniature camera and that wirelessly transmits video to a cellphone-sized computer in the wearer's pocket. This computer processes the image information and wirelessly transmits it to a tiny electronic receiver implanted in the wearer's head. 1 2 3