There may be new hope for people with certain types of blindness, as an experimental sight-restoring device has been deemed safe for implantation. It still has to be tested on humans, though, and it will likely provide a fairly rudimentary form of vision.
Known as the Phoenix99 Bionic Eye, the prosthesis is currently being developed by scientists at Australia's University of Sydney and University of New South Wales. It's intended for use on patients with blindness caused by degenerative conditions such as retinitis pigmentosa, in which the retina is compromised but the optic nerve remains intact.
The system incorporates a small video camera mounted on a pair of glasses, which images the scene in front of the wearer. Its output is converted into a wireless signal, which is transmitted from the camera to a communication module implanted under the skin behind the patient's ear.
That module in turn decodes the video signal into a pattern of electrical pulses, which are relayed to a stimulation module which is implanted on the retina in the affected eye(s). That device is able to bypass the retina's dysfunctional photoreceptor neurons, which have lost their ability to react to light focused onto the retina. Instead, the implant directly stimulates the underlying (and still functional) retinal ganglion cells, which are responsible for gathering input from other retinal cells and relaying it along the optic nerve to the brain.
"With regards to the quality of the restored vision, we know that it will be very different from what one would call normal vision," U Sydney biomedical engineer Samuel Eggenberger tells us. "Similar concepts of electrical stimulation of the retina have been tested in humans around the world and the results have been very variable, but expectations should be that the prosthesis will provide simple information about the person’s surroundings such as detecting obstacles, with the purpose to help with navigation, orientation or even reading of big letters."
In a recent three-month study, it was found that the Phoenix99 setup was well-tolerated by the bodies of sheep in which it was implanted. There were no reactions in the tissue surrounding the components, leading the scientists to believe that the system could safely remain in place for a number of years. The team is now applying for approval to conduct clinical trials on humans.
"We hope that through this technology, people living with profound vision loss from degenerative retinal disorders may be able to regain a useful sense of vision," says Eggenberger.
A paper on the sheep study was recently published in the journal Biomaterials.
Source: University of Sydney
