Bionic eye offers light at the end of the tunnel for the blind

Feb 18 2007

Researchers in the United States have been given the green light by the Food and Drug Administration (FDA) to trial a bionic eye implant in blind patients.

If all goes well the bionic eye implant could be available to patients within two years and could help restore the sight of millions of blind people.

The prototype device, the Argus II system, will be tested in 50 to 75 patients at five centres across the U.S. and uses a spectacle-mounted camera to feed visual information to electrodes in the eye.

Early tests with less-advanced versions of the retinal implant enabled patients to see light, shapes and movement.

Professor Mark Humayun, from the University of Southern California, says they are trying to take real-time images from a camera and convert them into tiny electrical pulses that will jump-start the otherwise blind eye and allow patients to see.

The bionic technology works by a camera on the patient's glasses viewing the image and sending signals to a hand-held device.

The processed information is passed back to the glasses and wirelessly transmitted to a receiver under the surface of the eye.

The receiver sends the information to electrodes in the retinal implant which stimulate the retina to send the information back to the brain.

Retinal implants have the potential to partially restore the vision of people with particular forms of blindness caused by diseases such as macular degeneration (AMD) or retinitis pigmentosa (RP).

As many as 1.5 million people worldwide develop retinitis pigmentosa, and one in 10 people over the age of 55 suffers from age-related macular degeneration.

The diseases affect the retinal cells which process light at the back of the eye and they gradually die; the new technology works by implanting an array of tiny electrodes into the back of the retina.

The process happens in real time and six patients have already been fitted with first-generation, low-resolution devices.

Humayun, a professor of ophthalmology at the Keck School of Medicine of USC and associate director of research at the Doheny Retina Institute, says one device has been implanted for five years.

Professor Humayun says there are 25 million people around the world, including 6 million in the United States, who have been blinded or are severely visually impaired due to diseases like RP and AMD.

Even with only 16 electrodes, the researchers have been surprised by how much the first six subjects have been able to do.

The new implant has a higher resolution than the earlier devices, with 60 electrodes and is considerably smaller, measuring around one square millimetre, which reduces the amount of surgery that needs to be done to implant the device.

A commercial version of the device would cost around $30,000.

Professor Humayun says other devices could be developed with higher a resolution or a wider field of view.

Professor Humayun says they are studying the effects the implants have on the brain and what happens to the visual cortex over time.

The research was presented at the American Association for the Advancement of Science (AAAS) annual meeting in San Francisco, US.