Full or partial blindness due to retinal disease affects an estimated
25 million people around the world. Macular degeneration (like that illustrated by the square pixelation behind the test subject, above) and other diseases destroy the photoreceptors in the eye that detect light and relay that data through the ganglion cells in the optic nerve to the brain.
But even when the photoreceptors are damaged, the ganglion cells typically remain alive and functional (see illustration at left). It occurred to Sheila Nirenberg, an associate professor at Weill Cornell Medical College, that if there were a way to artificially reproduce the complex code that a healthy retina produces when a person sees an image, then the brain could translate those signals, enabling a patient with macular degeneration to see again.
Using an array of high-speed, parallel processing computers, Nirenberg and her team embedded custom software in microprocessors and cameras that will be built into eyeglasses, such as the ones shown on this page. Images captured by the cameras will be translated into code in the form of thousands of pulsing lights, which can be recognized by the brain. The ganglion cells, when they encounter these lights, convert them into electric signals and send them on into the brain, which then reconverts the signals, allowing the patient to â??seeâ? the image.
Past attempts at restoring sight have typically used electrodes implanted deep in the eyeâ??and resulted in only limited and blurred vision. But Nirenbergâ??s team has developed an optogenetic procedure in which they inject a light-sensitive protein into the eye that â??focusesâ? data coming from the eyeglasses, producing results that are nearly as clear and focused as natural vision. The signals are so accurate that patients can recognize faces, animals, even the dimple in a babyâ??s smile.
The applications, in principle, extend far beyond vision. Sensory information could
be transmitted directly into the brain to
bypass faulty biological wiring, spinal
injuries, or damaged organsâ??almost any pathway our bodies use to convert information about the external world into data that our brains can understand.