Tuesday, 26 March 2013

Farsighted engineer invents bionic eye to help the blind

For UCLA bioengineering professor Wentai Liu, more than two decades of visionary research burst into the headlines last month when the FDA approved what it called “the first bionic eye for the blind.”

The Argus II Retinal Prosthesis System — developed by a team of physicians and engineers from around the country — aids adults who have lost their eyesight due to retinitis pigmentosa (RP), age-related macular degeneration or other eye diseases that destroy the retina’s light-sensitive photoreceptors.

At the heart of the device is a tiny yet powerful computer chip developed by Liu that, when implanted in the retina, effectively sidesteps the damaged photoreceptors to “trick” the eye into seeing. The Argus II operates with a miniature video camera mounted on a pair of eyeglasses that sends information about images it detects to a microprocessor worn on the user’s waistband. The microprocessor wirelessly transmits electronic signals to the computer chip, a fingernail-size grid made up of 60 circuits. These chips stimulate the retina’s nerve cells with electronic impulses which head up the optic nerve to the brain’s visual cortex. There, the brain assembles them into a composite image.

Recipients of the retinal implant can read oversized letters of the alphabet, discern objects and movement, and even see the outlines and some details of faces. And while the picture is far from perfect — the healthy human eye sees at a much higher resolution — it’s a breakthrough for people like the first patient, a man in his 70s who was blinded at age 20 by RP, to receive the implant in clinical trials. “It was the first time he’d seen light in a half-century,” said Liu, adding that “it feels good as the engineer” to have helped make this possible.

Liu joined the Artificial Retina Project in 1988 as a professor of computer and electrical engineering at
North Carolina State University. The multidisciplinary research project was funded by the U.S. Department of Energy’s Office of Science because it envisioned a potential pandemic of eyesight loss in America’s aging population. Leading the project was Duke University ophthalmologist and neurosurgeon Dr. Mark Humayun, now on faculty at USC. He tapped Liu to engineer the artificial retina.

“I thought it was a great idea,” Liu said. “But I asked, ‘What can I do?’ because I didn’t know much about biology.” Humayun handed him a six-inch-thick medical manual on the retina. “The learning curve was very steep,” Liu recalled with a laugh.

However, Liu’s fellow engineers questioned his sanity. “I was working on integrated chip design and had just gotten tenure when I signed on to this project. They said, ‘You’re crazy!’ But I’m glad I made that choice, getting into this new field.”