According to a new scientific breakthrough, a device - a tiny, three-by-three millimetre microchip, has allowed patients with inherited blindness to detect objects with their eyes, unlike a rival approach that uses an external camera. The procedure details are outlined in the journal Proceedings of the Royal Society B.
Professor Eberhart Zrenner, of Germany's University of Tuebingen, and colleagues at private company Retina Implant AG initially tested their sub-retinal chip on 11 people. Some showed no benefits from the procedure due to the advanced nature of their disease but a majority was able to pick out bright objects, Prof Zrenner said. He added that the further behind the retina the chip was placed, the better the results as seen in three patients. The blindness in these patients was due to the inherited condition retinitis pigmentosa (RP) in two and inherited condition called choroideraemia in another.
RP can start in childhood and leads to progressive blindness. This chip works by converting light that enters the eye into electrical impulses which are fed into the optic nerve behind the eye. Each implant contains 1,500 light sensors, which are connected to amplifiers and electrodes. The power for the chip comes via a cable which protrudes from the skin behind the ear to connect with a battery. Research is on to upgrade the device so that it is all contained beneath the skin, with power delivered though the skin via an external device that clips behind the ear.
Within days of having the implants, three of the patients could locate bright objects placed on a dark table. Two could also make out patterns. One patient could describe and name objects like cutlery or differing kinds of fruit. He could also locate people while walking around a room, and read large letters and words.
David Head, of the British Retinitis Pigmentosa Society said, “It's really fascinating work, but it doesn't restore vision. It rather gives people signals which help them to interpret.”
According to study authors, “The advantage of our approach is that all parts of the device can be implanted invisibly in the body, that inner processing can be used, and that a continuous, stable image with unmatched spatial resolution is perceived…The results of this pilot study provide strong evidence that the visual functions of patients blinded by a hereditary retinal dystrophy can, in principle, be restored to a degree sufficient for use in daily life.”
Further clinical trials are planned and a follow-up study are underway. Those studies should be completed in two to three years. If all goes well, the device could be on the market in about five years' time.