A bionic eye has helped people who are legally blind to see and read letters again.
The device consists of glasses with an embedded camera, and a microchip implanted behind the retina. Images beamed through the pupil from the camera are converted by the chip into electrical signals that are then sent to the brain.
Biotech firm Pixium Vision, which created the device, has trialled the bionic eye in five people in France who have age-related macular degeneration.
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All those in the trial had no central vision before the microchips were implanted. After 12 months, most have regained the ability to read individual letters and some can read sequences of letters. This represents a significant improvement, although it is still far from restoring perfect vision.
Macular degeneration affects the macula, the central 5 millimetres of the retina that is responsible for the middle part of vision. In severe cases, central vision is blurred or completely dark, making it impossible to read or recognise faces.
The bionic eye effectively replaces this missing central portion, although not in high definition. There are millions of photoreceptors in the retina, each of which is like a pixel in our field of vision. Trying to replicate that electronically is a challenge, but implants are improving, says Rachael Pearson at University College London, who wasn鈥檛 involved in the research. The image created by the Pixium implant is only 378 pixels in total.
Individuals with eye conditions can lose a huge number of photoreceptors before they notice symptoms. 鈥淏eing able to replace and do the job of a relatively small number may still give useful vision back,鈥� says Pearson.
All the trial participants have dry macular degeneration, a form of the condition that accounts for 90 per cent of all cases, and currently cannot be treated or reversed.
The implants could also be used to treat retinitis pigmentosa, a group of genetic conditions that result in the progressive loss of photoreceptors, says Mahi聽Muqit at Moorfields Eye Hospital in London, who was involved in the trial.
However, they cannot be used to treat people who are born blind, as the technique only works in people who have fully developed and intact optic nerves.
Other approaches are being tested that use electronic implants that bypass the eyes entirely and feed information directly to the visual processing centres of the brain. Elsewhere, researchers are using stem cells to .
Two clinical trials of the Pixium implant are currently under way in Pittsburgh and Miami in the US, and a larger study is planned for several centres across Europe next year.
