Australian researchers have announced a significant breakthrough in restoring some form of sight to blind patients such as spots of black and white light.

Dianne Ashworth, who has severe vision loss due to the inherited condition retinitis pigmentosa, has been fitted with a prototype bionic eye.

The device was designed, built and tested by scientists as the Australian Bionics Institute.

"It was really funny when it switched (on)," Ashworth said. "I didn't know what to expect and I don't know if anyone did know what I was going to see and then all of a sudden I went 'yep' I could see a little flash," she added. "When the first bigger image came I just went 'wow,' because I just didn't expect it at all but it was amazing."

The bionic eye is equipped with 24 electrodes with a small lead wire that extends from the back of the eye to a receptor attached behind her ear.

Artificial retinas require surgery to implant electrodes deep into the eye, stimulating cells that transmit information to the brain. The device restores mild vision, where patients are able to pick up major contrasts and edges such as light and dark objects.

Researchers hope to develop the prototype so blind patients can achieve independent mobility.

Dr Lauren Ayton, from the Centre for Eye Research Australia said: "With the prototype the idea is to stimulate the retina to give little spots of light, which are called phosphenes, and so, with her implant, Di will be able to see a number of spots in different locations and will be able to see things like shapes and the edges of doorways and objects like that eventually."

Two more volunteers have now undergone the four and a half hour operation and are waiting for their devices to be switched on.