An Australian woman has been the first recipient of a prototype bionic eye with 24 electrodes, which has succeeded in restoring some of her vision.
Dianne Ashworth has profound vision loss due to retinitis pigmentosa, an inherited condition. Last month, the implant - developed by Bionic Vision Australia, was switched on.
"I didn't know what to expect, but all of a sudden, I could see a little flash...it was amazing. Every time there was stimulation there was a different shape that appeared in front of my eye," she says.
The prototype consists of a retinal implant with 24 electrodes. A small lead wire extends from the back of the eye to a connector behind the ear. An external system is connected to this unit in the laboratory, allowing researchers to stimulate the implant in a controlled manner in order to study the flashes of light.
Feedback from Ms Ashworth will allow researchers to develop a vision processor so that images can be built using flashes of light.
"This is a world first - we implanted a device in this position behind the retina, demonstrating the viability of our approach," says Dr Penny Allen, who led the surgical team carrying out the implant.
"Every stage of the procedure was planned and tested, so I felt very confident going into theatre."
The team is now working with Ms Ashworth to to determine exactly what she sees each time the retina is stimulated, looking for consistency of shapes, brightness, size and location of flashes to determine how the brain interprets this information.
The team's now working on a wide-view implant with 98 electrodes and a high-acuity version with 1,024 electrodes. Patient tests are planned for these devices in due course.
"These results have fulfilled our best expectations, giving us confidence that with further development we can achieve useful vision," says professor emeritus David Penington, chairman of Bionic Vision Australia.
"Much still needs to be done in using the current implant to 'build' images for Ms Ashworth. The next big step will be when we commence implants of the full devices."