"We Don't See with Our Eyes" Device Pushes the Limits of Vision

By Allyson T. Collins
NEI Science Writer/Editor

Erik Weihenmayer wears sunglasses often. He was wearing them to protect his eyes when he reached the summit of Mount Kilimanjaro in 1997. He had them on when he completed the 2003 Primal Quest, the world's toughest multi-sport adventure race. And, he put on a pair during a recent visit to the National Eye Institute (NEI).

But this last set is no ordinary pair of Oakley sunglasses.

Weihenmayer looks through them, peering down at a white note card on a table. He silently moves his head back and forth, up and down. After a few moments, he says, "Is that a 12?"

Richard Hogle, sitting next to him, nods his head. "Yep," he confirms, "and you were still well zoomed out." The sunglasses are wirelessly connected to Hogle's laptop, so he can monitor Weihenmayer's view. "I'm amazed," Hogle comments.

Weihenmayer laughs. "How could I make money off this device?" he asks. "Doing some kind of card trick at a party...I could really freak people out!"

He is one of only 40 people ever to use this specially outfitted type of sunglasses, but all have one thing in common: they're blind.

The sunglasses are part of a breakthrough vision device known as BrainPort, under development by the NEI-supported researchers of Wicab, Inc., for which Hogle serves as director of product development. BrainPort is built on the concept of sensory substitution, which means that when one sense malfunctions, another sense can compensate, serving as a stand-in.

"Even a blind person walking down the street with a cane is basically using a form of sensory substitution," says Michael D. Oberdorfer, Ph.D., of the NEI extramural research program.

With BrainPort, the tongue ultimately replaces the eyes in transmitting visual input to the brain. But first, a small video camera on the nose bridge of the sunglasses acts as "eyes" to gather visual information. The images are transmitted in black, gray and white to a handheld computer, slightly larger than an iPod, which translates the visual information into electrical signals.

Next, these signals are transformed into gentle electrical impulses that end up on the tongue when BrainPort users place a lollipop-sized electrode array in their mouths.

The white portions of images become strong impulses, the gray become medium impulses, and the black result in no impulses. The tongue sends these impulses to the brain, where they are interpreted as sensory information that substitutes for vision. 

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