10.05.2016

New artificial retina "could restore vision"

New artificial retina "could restore vision"

The fight against blindness has been raging for centuries, with many developments coming and going, but a new one appears to offer hope to people who are losing their vision.

For the first time, experts have been able to decipher the retina's neural code for brain communication to create a novel, more effective prosthetic retinal device for blindness.

The breakthrough has been made by two researchers at Weill Cornell Medical College, who have deciphered a mouse's retina's neural code and coupled this information to a novel prosthetic device to restore sight to blind mice.

The researchers claim that they have also cracked the code for a monkey retina - which is essentially identical to that of a human - and are hoping to quickly design and test a device that blind humans can use.

Published in the Proceedings of the National Academy of Sciences, the study signals a remarkable advancement in the longstanding efforts to restore vision, following current prosthetics that provide blind users with spots and edges of light to help them navigate.

The new device takes things a step further by providing the code to restore normal vision, which is so accurate that it can allow facial features to be discerned and allow animals to track moving images.

According to lead researcher, Dr Sheila Nirenberg, a computational neuroscientist at Weill Cornell, he envisions a day when the blind can choose to wear a visor, similar to the one used on the television show Star Trek.

The visor's camera would take in light and use a computer chip to turn it into a code that the brain can translate into an image, the expert reasoned.

"It's an exciting time. We can make blind mouse retinas see, and we're moving as fast as we can to do the same in humans," she noted.

Dr Nirenberg, a professor in the Department of Physiology and Biophysics and in the Institute for Computational Biomedicine at Weill Cornell, carried out the research along with co-author Dr Chethan Pandarinath, who is currently a postdoctoral researcher at Stanford University.

They say the new approach provides hope for the 25 million people worldwide who suffer from blindness due to diseases of the retina and, because drug therapies help only a small fraction of this population, prosthetic devices may be the best option to guarantee future sight.

As Dr Nirenberg explained: "This is the first prosthetic that has the potential to provide normal or near-normal vision because it incorporates the code."

The research was based on the reasoning that any pattern of light falling on to the retina had to be converted into a general code that turns light patterns into patterns of electrical pulses.

"People have been trying to find the code that does this for simple stimuli, but we knew it had to be generalisable, so that it could work for anything — faces, landscapes, anything that a person sees," she noted.

While working on the code for a different reason, Dr Nirenberg realised that what she was doing could be directly applied to a prosthetic and quickly implemented the mathematical equations on a chip and combined it with a mini-projector.

The chip converts images that come into the eye into streams of electrical impulses, with the mini-projector then converting the electrical impulses into light impulses.

These light pulses then drive the light-sensitive proteins, which have been put in the ganglion cells, to send the code on up to the brain.

Dr Nirenberg explained that the encoder is able to mimic retinal transformations for a broad range of stimuli, including natural scenes, and thus produce normal patterns of electrical pulses, while a stimulator, or light sensitive protein, is able to send those pulses on up to the brain.

"What these findings show is that the critical ingredients for building a highly-effective retinal prosthetic - the retina's code and a high resolution stimulating method - are now, to a large extent, in place" the expert said.

"This has all been thrilling. I can't wait to get started on bringing this approach to patients," she concluded.ADNFCR-1853-ID-801429748-ADNFCR


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