A team of researchers believe implanting photovoltaic technology, like the solar panels on your roof, into the human eye could be the key to restoring vision.
UNSW engineer and photovoltaic specialist Dr Udo Roemer is in the early stages of researching how solar technology can be used to convert light entering the eye into electricity, bypassing the damaged photoreceptors to transmit visual information to the brain.
While it might sound like something out of science fiction, neuroprosthetics – or devices designed to interact with the nervous system to restore lost functionality – have already been helping Australians vastly improve their quality of life for years.
One of the best-known examples is the cochlear implant, which converts sound into electric signals that directly stimulate the auditory nerve in people with severe hearing loss.
But it remains to be seen if the same can be done for the human eye to restore vision for people with damaged photoreceptors—the cells responsible for detecting light and colour.
“People with certain diseases like retinitis pigmentosa and age-related macular degeneration slowly lose their eyesight as photoreceptors at the centre of the eye degenerate,” Dr Roemer says.
“It has long been thought that biomedical implants in the retina could stand in for the damaged photoreceptors. One way to do it is to use electrodes to create a voltage pulse that may enable people to see a tiny spot.
“There have already been trials with this technology. But the problem with this is they require wires going into the eye, which is a complicated procedure.”
Alongside a small global team of researchers, Dr Roemer says their alternative tiny wireless, self-powered solar panel alternative could be a more accessible option that would revolutionise how the world tackles vision loss.
But it won’t be cheap. The doctor said the implant would need to use costly semiconductor materials such as gallium arsenide and gallium indium phosphide that are used in the solar industry at large to make much more efficient solar panels.
“In order to stimulate neurons, you need a higher voltage than what you get from one solar cell,” Dr Roemer says.
“If you imagine photoreceptors being pixels, then we really need three solar cells to create enough voltage to send to the brain. So we’re looking at how we can stack them, one on top of the other, to achieve this.
“With silicon this would have been difficult, that’s why we swapped to gallium arsenide where it’s much easier.”
While Dr Roemer and his team say the technology is promising, don’t expect to see solar-panelled-faced pedestrians anytime soon. The technology is still very much in the proof-of-concept stage, with the next step being to make the solar cells into tiny pixels required for sight.
“So far we’ve successfully put two solar cells on top of each other in the lab on a large area – about 1cm2, which has got some good results.”
Dr Roemer envisages by the time this technology will be able to be tested in humans – after extensive testing in the lab, followed by testing in animal models – the device will be about 2 mm2 in size with pixels measuring about 50 micrometres (five hundredths of a millimetre).
He stresses that it’s still a long way off before this technology will be implantable in the retinas of people with degenerative eye diseases.
“One thing to note is that even with the efficiencies of stacked solar cells, sunlight alone may not be strong enough to work with these solar cells implanted in the retina,” he says.
“People may have to wear some sort of goggles or smart glasses that work in tandem with the solar cells that are able to amplify the sun signal into the required intensity needed to reliably stimulate neurons in the eye.”
