As you look at this page, your eyes are doing a remarkable thing.

A stream of light from the words and pictures is bouncing into the eyeball and falling onto photoreceptor cells on the retina. This visual information is passed on to output cells and then transmitted to the brain as a kind of code, where it is reconstructed to make up the letters in this sentence you are reading right now.

Degenerative eye diseases, however, can wreak havoc on this process, says neuroscientist Sheila Nirenberg of Weill Medical College at Cornell University. When they damage the retina, the image in front of you never gets further than the eyeball; the chain is broken.

That’s what makes the technology that Nirenberg has built rather remarkable. She has found a way to transmit a visual code directly to the brain, bypassing damaged cells in the eye. In other words, she can help the blind see again.

In the video above, she explains how her technology works and the eureka moment that started it all.

Watch and read more from our series The Genius Behind: the most amazing and sometimes little-known technological and scientific breakthroughs of modern times, and the innovative minds behind them.

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