Scientists have developed an ‘extremely promising’ technology that could one day help blind people see light.
Millions of people worldwide are unable to see anything. Although this is often due to faults in the retina, only a few hundred qualify for retinal implants.
The retina is at the back of the eye and picks up on images the optic nerve then converts into impulses. These are sent to the brain, where a picture is formed.
Researchers from Switzerland and Italy delivered an electric current directly to the optic nerve of rabbits via an electrode called OpticSELINE.
This stimulated the animals’ visual cortex, the region of the brain where information from the retinas is processed.
It is unclear whether this would enable a blind person to see, but proves the technology’s ‘potential’, the researchers claim
The technology delivered an electric current directly to the optic nerve of rabbits via an electrode called OpticSELINE (pictured). The device measures at around 11cm (4.3inches)
The technology was created by teams at the École polytechnique fédérale de Lausanne, Switzerland, and Scuola Superiore Sant’Anna, Italy.
Around 39million people in the world are blind, the researchers wrote in the journal Nature Biomedical Engineering.
Vision loss caused by infection, inflammation or retinal detachment, when it comes loose, can often be treated.
Retinal implants have been suggested for the genetic disorder retinitis pigmentosa, which occurs when cells in the retina break down. This affects half-a-million people worldwide.
The procedure involves replacing damaged retinal cells with electronic implants that stimulate the remaining healthy cells to produce a signal along the optic nerve.
This requires a small cut in the eye, with no guarantee of good vision. It is not available on the NHS.
Scientists have been attempting to restore vision by stimulating the optic nerve since the 1990s.
Professor Diego Ghezzi, medtronic chair in neuroengineering at EPFL, said: ‘Back then, they used cuff nerve electrodes.
‘The problem is these electrodes are rigid and they move around, so the electrical stimulation of the nerve fibers becomes unstable.
‘The patients had a difficult time interpreting the stimulation, because they kept on seeing something different.’
With the recent technology, the scientists used intraneural electrodes. These are administered directly into the optic nerve, while cuff varieties surround the nerve.
‘The translational potentials of this approach are indeed extremely promising,’ said co-author Professor Silvestro Micera.
OpticSELINE was created out of 12 electrodes, which together delivered an electric current to the rabbits’ visual cortex.
The researchers monitored activity in this part of the brain and developed an ‘elaborate algorithm’ to decode the signals.
They found each electrode led to a ‘specific and unique pattern of cortical activation’. This suggests the optic nerve is ‘selective and informative’, they wrote.
‘For now, we know that intraneural stimulation has the potential to provide informative visual patterns,’ Professor Ghezzi said.
‘It will take feedback from patients in future clinical trials in order to fine-tune those patterns.
‘From a purely technological perspective, we could do clinical trials tomorrow.’
‘Current electrode technology’ means a human OpticSELINE would be made of between 48 and 60 electrodes, the researchers wrote.
This would be insufficient to restore sight entirely but could provide blind people with a visual aid that makes day-to-day life easier, they added.