Seeing the light - without wires

SMALL PRINT:IT SOUNDS LIKE something out of science fiction, but researchers in the US have developed a "solar" implant for the eye. While there's a way to go yet, the hope is that it might eventually help people with vision loss due to certain forms of degeneration of the retina, the light-sensitive tissue at the back of the eye.

The approach puts a tiny solar-panel-like implant under the retina. To use it, the person would wear special video goggles. When the video goggles capture an image from the person’s surroundings, near-infrared lasers would beam the information to the implanted photovoltaic silicon chip. This would activate light-sensitive diodes on the chip and electrical currents would trigger activity.

“It works like the solar panels on your roof, converting light into electric current,” said researcher Daniel Palanker, associate professor of ophthalmology at Stanford, in an article on the university’s website. “But instead of the current flowing to your refrigerator, it flows into your retina.”

By putting so much hardware into the goggles – rather than into the person – and by using near-infrared light to send the signal, the approach looks to cut down on the bulkiness and wiring of retinal prostheses, and to make it easier to insert them surgically. “The surgeon needs only to create a small pocket beneath the retina and then slip the photovoltaic cells inside it,” says Palanker. But while other retinal implants are already in clinical trials in humans, this approach is at an earlier stage. A paper out this week in Nature Photonics describes how the researchers studied the effects of the implants on normal and degenerative rat retinas. Pre-clinical work is ongoing.