Photokina 2014 highlights

New light-powered retinal prosthesis could restore sight to the blind

By

May 15, 2012

A new retinal prosthesis could allow the blind to see, by using pulses of near-infrared li...

A new retinal prosthesis could allow the blind to see, by using pulses of near-infrared light to activate the retinal neurons in their eyes (Image via Shutterstock)

Image Gallery (2 images)

Age-related macular degeneration is the leading cause of blindness in North America, while retinitis pigmentosa causes approximately 1.5 million people worldwide to lose their sight every year. Individuals afflicted with retinal degenerative diseases such as these might someday be able to see again, however, thanks to a device being developed at California’s Stanford University. Scientists there are working on a retinal prosthesis, that uses what could almost be described as miniature solar panels to turn light signals into nerve impulses.

The system consists of a camera- and microprocessor-equipped pair of goggles, and a small photovoltaic chip that is implanted beneath the retina.

The output of the camera is displayed on a miniature LCD screen, located on the inside surface of the goggles. That screen is special, however – it emits pulses of infra-red laser light, that correspond to the images it’s displaying. Photodiodes on the chip register those pulses, and in turn stimulate retinal neurons. In theory, this firing of the neurons should produce visual images in the brain, as would occur if they had been stimulated by visible light.

“It works like the solar panels on your roof, converting light into electric current,” said Dr. Daniel Palanker, associate professor of ophthalmology. “But instead of the current flowing to your refrigerator, it flows into your retina.”

Palanker’s team has created a chip about the size of a pencil point, which is thinner than a human hair, and contains hundreds of the photodiodes. These were tested using retinas from both sighted rats, and rats that were blind in a fashion similar to human degenerative blindness – the retinal neurons were still present, but were generally inactive. While the chips in the blind retinas didn’t respond to visible light (unlike those in the sighted retinas), they did respond to the near-infrared light. “They didn't respond to normal light, but they did to infrared,” said Palanker. “This way the sight is restored with our system.”

The photovoltaic chip is implanted under the retina in a blind rat (upper right corner) – ...
The photovoltaic chip is implanted under the retina in a blind rat (upper right corner) – it is comprised of an array of photodiodes (center and lower left) (Image: Palanker Laboratory/Stanford University)

The scientists are currently testing the technology on live rats, and state that it so far looks as if the electrical signals are indeed reaching the rats’ brains. They are now looking for a sponsor for human trials. Palanker notes that the system doesn’t allow for color vision, however, and that what vision is does provide would be “far from normal.”

While other retinal prostheses are also in development, these reportedly involve more in the way of hardware such as coils or antennas being implanted in the eye. Most of the technology used in the light-based Stanford system, by contrast, is located in the goggles.

A paper on the research was published this week, in the journal Nature Photonics.

Source: Stanford University Medical Center

About the Author
Ben Coxworth An experienced freelance writer, videographer and television producer, Ben's interest in all forms of innovation is particularly fanatical when it comes to human-powered transportation, film-making gear, environmentally-friendly technologies and anything that's designed to go underwater. He lives in Edmonton, Alberta, where he spends a lot of time going over the handlebars of his mountain bike, hanging out in off-leash parks, and wishing the Pacific Ocean wasn't so far away.   All articles by Ben Coxworth
Tags
Post a Comment

Login with your gizmag account:

Or Login with Facebook:


Related Articles
Looking for something? Search our 28,518 articles