A pioneering retina-implant surgery has been successful in Germany. After fitting an experimental chip behind his retina, Miikka Terho, 46, from Finland, who had an inherited form of blindness, has been able to see.

Unlike normal approaches where the patient uses an external camera, the chip allowed him to detect objects with his own eyes instead.

The sub-retinal chip was tested on 11 patients by Professor Eberhart Zrenner, of Germany's University of Tuebingen, and colleagues at private company Retina Implant AG.

Though it did not prove successful with all of them, as some were at advanced stages, a wide majority of them were able to identify bright objects. Three of them achieved best results, two of whom had lost their vision because of the inherited condition retinitis pigmentosa, or RP, the other because of a related inherited condition called choroideraemia.

Researchers noted that RP leads to slow degeneration of cells in the retina, resulting in night blindness, tunnel vision, that later makes the patient permanently blind. These symptoms can begin from early childhood.

Mr Terho, one of them who undertook the retinal implant was found most successful as he was able to recognize cutlery, a mug on a table, a clock face. In fact, he was able to move around without external help, which was mind blowing. He later even read large letters, including his misspelled name.

"Three or four days after the implantation, when everything was healed, I was like wow, there's activity," he told the BBC from his home in Finland. "Right after that, if my eye hit the light, then I was able to see flashes, some activity which I hadn't had.

"Then day after day when we started working with it, practicing, and then I started seeing better and better all the time."

Explaining how the chip works, scientists note that the light that enters the eye is converted into electrical impulses, which are later fed into the optic nerve behind the eye. The chip was powered through an external source during the study.

Doctors are now working on an upgraded version of the implant, after getting good results through the prototype. They are trying to work on a mechanism through which power will be delivered through an external device via the skin.

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."