Last updated March 8, 2018 at 9:45 am
Chinese experiment brings hope to sufferers of degenerative eye diseases.
Diseases such as retinitis pigmentosa or macular degeneration are responsible for around 50 per cent of all cases of blindness in Australia.
They lead to a constant degrading of vision, with every day getting slightly worse, the edges darkening and closing in until it’s like looking down a narrow pipe.
However, a team of Chinese researchers have sparked hope of a treatment for degenerative eye diseases, developing nanowires which can be implanted in the eye and restore sight.
Solar cells for the eye
The team of researchers, led by Jiayi Zhang from Fudan University in Shanghai, coated titanium dioxide nanowires with gold nanoparticles. These gold particles, just 10nm in size and tightly bound to the titanium wire, create a photovoltaic effect similar to that of solar cells on the roof of your house.
When exposed to light, the gold/nanowire complex generates a voltage, which can then be transmitted to neighbouring neurons. These voltages can help restore vision signalling.
The gold and titanium nanowires are implanted into diseased retina as artificial photoreceptors. Credit: Tang et al
To test this approach, the researchers implanted the nanowires in mice. The wires were placed into the retina replacing defective photoreceptor cells, and effectively became arrays of artificial photoreceptors.
They found that the wires restored electrical signalling and pupil dilation when the mice were exposed to green, blue and ultraviolet light.
More excitingly though, in the brains of the mice the scientists could detect light-evoked activity in the primary visual cortex. This, they say, confirms the restoration of visual function just 4–8 weeks after implant surgery.
Importantly, the implant was also well tolerated by the mice.
As the nanowires are sensitive to all light sources, the vision information it creates is just the presence of light – ie black and white. However, the scientists think that the nanowire arrays could be adapted to create colour vision.
To achieve this, they would need to develop different nanowire types that only react to certain coloured light, for example one that is sensitive to red and a different nanowire type sensitive to green light. The signals from these wires would then have to be slightly different so that they can be differentiated. Finally, the visual cortex would need to be retrained to recognise the different signals and process those as being indicative of different colours.
The next generation of prosthetics for vision
The work could lead to the design of better prosthetics that do not require external power sources and are capable of colour vision.
The nanowires are a considerable improvement over other protheses used to restore vision, which devices require implanting a light detecting array that detects signals from a video-capture camera.
It is thought this approach could be particularly useful to treat degenerative diseases such as retinitis pigmentosa or macular degeneration, which untreated, leads to loss of vision and blindness.
While the nanowires have so far only been trialled in mice, it is hoped that they could be tested in humans in the future. If successful, these nanowires could open up new treatment options for people at risk of long-term visual degeneration.
The research has been published in Nature
