Retinitis Pigmentosa is a sentence of darkness: most of the estimated 1.5 million victims worldwide either have or will go irreversibly blind before the age of 40.
But a multidisciplinary research team led by Gregg Suaning, Professor of Biomedical Engineering at the University of Sydney, has developed a new bionic eye that promises to revolutionise the lives of sufferers.
RP is an incurable genetic disorder that gradually destroys the ability of the retina to convert light into electrical signals that are then transmitted to the brain via the optic nerve.
Professor Suaning and his team have developed a ceramic and platinum retinal implant that mimics the retina, converting signals from an external camera mounted on a pair of spectacles into electrical impulses that stimulate the undamaged nerves behind the retina via a radio frequency coupling implanted behind the ear. Wearers “see” a pattern of spots of light called phosphenes: the spots of light one sees when rubbing one’s eyes.
“It’s like a jumbotron at a sports game,” says Professor Suaning. “The individual light spots come together to give a recognisable image.”
The principles behind the system are similar to those used in a cochlear implant, but with the Phoenix99, the University of Sydney team is pushing the boundaries. A cochlear implant typically has less than 25 electrodes: the bionic eye has 98.
“Australia has an impressive record in medical technology. The pacemaker was developed here, and we were leaders in cochlear implants. But developing devices like this is expensive, if we had a commercial partner, it would be much easier”
Professor Suaning says that collaboration has been at the heart of his team’s success. He is a leading biomedical engineer in the Faculty of Engineering and IT, but he has been working with his colleagues in the School of Information Technology to develop the software to convert the camera image, and with clinicians from Sydney Medical School, the Save Sight Institute and Westmead Hospital, creating a cluster of expertise that has pushed the technology forward.
He says that the team has hit the limits of current materials technology – any more electrodes in the array and electrical interference begins to degrade the image – but he believes that Phoenix99 can be further improved.
“In principle, we should be able to use a pair of cameras to give an impression of distance, with different colours indicating that objects are nearer or further away,” he says.
And the technology has potentially much wider applications.
“This could use to give a sense of touch to people with bionic prosthetics. They could feel pressure or heat in the objects they touch. We could help people with facial paralysis; they can’t feel when their eyes are getting dry they don’t blink and that can lead to blindness. We could use electrode implants attached to a sensor to tell them when they need to blink.”
Professor Suaning is preparing the Phoenix99 for clinical trials, but he believes the next challenge will be to scale up production. All the implants are currently hand-built in the laboratory across the corridor from his office. “Australia has an impressive record in medical technology. The pacemaker was developed here, and we were leaders in cochlear implants. But developing devices like this is expensive, if we had a commercial partner, it would be much easier,” he says.