Electrodes made of diamond are helping Melbourne researchers build a better bionic eye.

Some types of blindness are caused by diseases where the light-sensing part of the retina is damaged, but the nerves that communicate with the brain are still healthy—for example, retinitis pigmentosa and age-related macular degeneration.

Dr David Garrett and his colleagues at the Melbourne Materials Institute at the University of Melbourne are using diamond to build electrodes that can replace the light-sensing function of the retina: they deliver an electrical signal to the eye via a light-sensing camera.

These electrical impulses would cause the healthy neurons in the retina to fire and send visual information to the brain—restoring a sense of sight.

But the functionality of the first bionic eye implants will be limited. Patients will need to learn and adjust to this new sense of vision to tell the difference between light and dark and recognise basic shapes.

“Like with the bionic ear, software may be able to greatly improve on the original hardware.” David says. “Because of Melbourne’s history with the cochlear implant and the infrastructure here, we’re making progress quite quickly.”

Diamond has been used before in other non-bionic implants but there are two reasons it suits the bionic eye project. First, lacing diamond with nitrogen makes it conduct electricity, enabling electrodes to link up with the existing nervous system. Second, diamond is not prone to corrosion, infection or breaking down in the body, even after many years.

“You want these devices to last as long as possible—and for that you can’t beat diamond,” David says.

Photo: David Garrett’s Melbourne team is designing diamond electrodes to replace light-sensing parts of the retina

Credit: David J. Garrett

Melbourne Materials Institute, David Garrett, dgarrett@unimelb.edu.au, materials.unimelb.edu.au