December 23, 2009

Bionic Eye ‘Sees’ Daylight

The development of a bionic eye that will restore vision to someone who is completely blind is a step closer after the research team working on the project detected signals in the brain from electrodes implanted in the retina of a living eye.

The project, led by Associate Professor Michael Ibbotson from The Vision Centre and The Australian National University, has been investigating how artificial electrical signals can be converted into meaningful biological signals in the eye. It uses a wafer-thin stimulating device that can be implanted in animal and human eyes, which was developed at the University of New South Wales by Professor Nigel Lovell and Associate Professor Gregg Suaning.

The latest development in the research has shown that it is possible for electrical stimulation of the retina to provide a meaningful pattern of simulation in those parts of the brain that generate visual perception.

"This is a very exciting development," says Associate Professor Ibbotson. "The device that's been created seems to work really well "“ beyond our expectations.

Delicately slipped into the choroid "“ the dark-colored layer in the outer eyeball "“ the array of electrodes sent electrical signals to the optic nerve, which then transmitted them to the brain where they were detected using sophisticated optical imaging techniques.

The research was carried out in an animal model under strict anesthetic conditions. "We know the device is working because we were able to compare the spatial pattern of visual stimulation with the pattern of electrical stimulation," he explains.

"We don't yet know what these signals look like to a human observer, but we can see that they will have an influence on perception because we've detected them in the correct parts of the brain. Most probably they are phosphenes, which are the swirly patterns you see when you press your closed eye," he said.

The experimental device uses an array of stimulating electrodes substituting for photoreceptors in a healthy eye. In the healthy eye photoreceptors detect light and dark, sending tiny electrical impulses down the chain of cells linked to the optic nerve, which then transmits them to the brain.

"As we increase the number of electrodes and add in some electronic signal processing it will theoretically be possible to convert the phosphene blobs into meaningful images and to have enough vision to recognize faces and even text."

"Our results strongly encourage us to believe that the devices being developed will be able to achieve functional vision in humans "“ enough to recognize faces, patterns and perhaps even letters. It's remarkable how much vision you can achieve with very little visual information."

Professor Ibbotson's group is part of a four-university research consortium (Bionic Vision Australia) which was last week awarded $42 million funding by the Federal Government.

The Vision Centre is funded by the Australian Research Council as the ARC Centre of Excellence in Vision Science.


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