A bionic eye has enabled blind people to read letters and simple words.
The implant converts images from an external camera into electronic signals that the brain can "see".
Tests on 21 patients with retinitis pigmentosa, a degenerative disease that destroys light-receiving cells at the back of the eye, showed that three quarters were able to correctly identify single letters.
More than half were able to read four-letter words, according to results published in the British Journal of Ophthalmology.
Before being fitted with the device Richard Barrett only had vague light perception in one eye.