Surgeons have successfully implanted a pioneering bionic eye in two blind patients at London’s Moorfields Eye Hospital. It is hoped that it could be used in the future help to restore blind people’s sight.

The device — the Second sight Argus II — uses a video camera to capture images. These are converted into electrical signals, which are transmitted wirelessly to the implant behind the retina. The electrodes in the implant unscramble the signal to create a crude black-and-white picture that is relayed along the optic nerve to the brain. The brain can then perceive patterns of light and dark spots corresponding to the electrodes stimulated.

The device is only useful for those blinded by Retinitis Pigmentosa but can return a degree of sight to other sufferers, allowing them to see light and shade and in which direction an object is moving.

The identities of the British patients have been concealed while doctors monitor their progress.