Blind people could be able to regain some of their sight, according to new research.
A new technique is being pioneered involving an implant which stimulates the optic nerve, using electrodes to send messages to the brain – and bypassing the eyeball completely.
The device, called OpticSELINE, has been successfully tested in white rabbits, and scientists are hopeful of similar results in humans.
It could treat people with glaucoma, the world’s second leading cause of blindness, and other conditions where the nerve connecting the eye to the brain is damaged.
In the lab animals the array of 12 electrodes was surgically implanted using a needle and triggered the visual cortex – the part of the brain that processes images.
Co-author Professor Silvestro Micera, a neuro-engineer at the Swiss Federal Institute of Technology (EPFL) in Lausanne, said: ‘We believe intraneural stimulation can be a valuable solution for several neuro-prosthetic devices for sensory and motor function restoration.
‘The translational potentials of this approach are indeed extremely promising.’
With current electrode technology, a human OpticSELINE could consist of up to 48-60 electrodes.
This is not sufficient to restore sight completely, but it would be enough to provide a visual aid for daily living.
This would include getting dressed and moving about withoput bumping into objects – restoring independence to the blind.
The idea is to produce phosphenes, the sensation of seeing light in the form of white patterns to show up the edges of objects. The constellation of dots has been likened to stars that glitter and fade behind passing clouds.
The same team unveiled the first bionic hand with a sense of touch last year, using a similar intraneural electrode.
The recipient, Almerina Mascarello, who lost her left hand in an accident a quarter of a century ago, said ‘it’s almost like it’s back again.’
Blindness affects around 39 million people across the globe with many causes – from genetics, detached retinas and trauma to stroke, cataracts, infections and glaucoma.
To demonstrate OpticSELINE’s effect the researchers delivered an electric current to the nerve and used a complex algorithm to decode the signals in the visual cortex of the blind rabbits.
Each stimulating electrode induced a specific and unique pattern of hundreds of specks of white light, or phospheses, to make up an image.
The optic nerve the main nerve that transmits images from the eye to the brain, allowing us to see.
As a preliminary study the degree of visual perception remains unknown. But it suggests the device described in Nature Biomedical Engineering is ‘selective and informative’, they said.
Co author Prof Diego Ghezzi said: ‘For now, we know intraneural stimulation has the potential to provide informative visual patterns.
‘It will take feedback from patients in future clinical trials in order to fine tune those patterns.’
He added: ‘From a purely technological perspective, we could do clinical trials tomorrow.’
