It comprises a computer chip that sits in the back of the individual's eye, linked up to a mini video camera built into glasses that they wear.

Images captured by the camera are beamed to the chip, which translates them into impulses that the brain can interpret.

The device has been designed by Professor Gislin Dagnelie at Johns Hopkins University, Baltimore.

Human trials will begin within a year, hopes Professor Dagnelie.

Although the images produced by the artificial eye were far from perfect, they could be clear enough to allow someone who is otherwise blind to recognise faces, he said.

The breakthrough is likely to benefit patients with the most common cause of blindness, macular degeneration, which affects 500,000 people in the UK.

This is a revolutionary piece of technology and really has the potential to change people's lives   Anita Lifestone of the Royal National Institute for the Blind

This occurs when there is damage to the macula, which is in the central part of the retina where light is focussed and changed into nerve signals in the middle of the brain.

The implant bypasses the diseased cells in the retina and stimulates the remaining viable cells.

See the light

Professor Dagnelie said: "The retinal implant contains tiny electrodes. If you stimulate a single electrode, the person will see a single dot of light."

They have already tested implants containing a handful of electrodes, but the end device will contain 50-100 to give a better overall picture.

"We are hoping this will be enough for the person to be able to make their way through a building, find a door or window and avoid obstacles for example.

"To us, the images look very basic but for someone who was previously blind they are a massive step forward."

But he added: "There is still quite a bit of work that will be needed to fine tune it. Being able to see faces will be quite a bit down the line."

He said training the individual to learn how to interpret the blurry images should help.

Anita Lifestone of the RNIB, said: "This is a revolutionary piece of technology and really has the potential to change people's lives. But we need to be aware it is still some way in the future."

Story from BBC NEWS UK Edition