Bionic eye

Peter Weekes
February 18, 2007

MELBOURNE'S Eye and Ear Hospital will start implanting bionic eyes that restore sight to the blind within a few years.

The hospital is one of three centres outside the United States that have been chosen to implant the revolutionary device developed by the Doheny Eye Institute at the University of Southern California.

American scientists said last week that the first six patients to try the bionic eye had learnt how to detect light, distinguish between objects and perceive direction of motion.

"We expected that all they would be able to do would be to differentiate between light and dark.

But we were amazed to find that they can tell the difference between objects such as a plate, a knife and a cup, and tell which way people are moving," said Professor Mark Humayun of the University of California, who led the research.

His team is preparing to test a more advanced version of the implant on as many as 75 patients.

"If the new trial hits its milestones, the second-generation implant could be commercially available in two years," Professor Humayun said.

The device offers hope to millions of people who have lost their vision to retinitis pigmentosa, a group of inherited eye diseases that cause the degeneration of the photoreceptor cells that capture and process light. It is the most common cause of blindness among those under 50.

The implant is not suitable for every form of blindness, but scientists hope that it might be used to restore the sight of those with degenerative eye diseases, particularly those with macular degeneration who are over 75.

Professor William Campbell, head of the Royal Victorian Eye and Ear Hospital's vitro retinal unit, described the device as "the beginning of a very exciting development in opthamology".

"We have been chosen to be one of the centres around the world where they want to put in their implants, but it will be two or three years before we start doing it. We will be putting some of the early models in when we find suitable candidates and after we have been trained."

The device comes in two parts. A tiny camera in the lens or on the bridge of a pair of lightweight glasses captures images.

This information is transmitted to a radio receiver implanted behind the patient's ear that converts it to electrical signals, which are sent to a grid of electrodes implanted in the retina.

These electrodes stimulate retinal nerve cells to produce electrical impulses that send signals to the brain so the patient can see spots of light in different patterns.

While the first-generation device had 16 electrodes, the new one has 60 electrodes and will cost about $32,000.

The first device took 16 years of research, but the second version has taken just four years.

Source: The Sun-Herald