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Robotic retina offers second chance for sight

Six blind patients have had their sight partially restored by a ‘bionic eye’ surgically implanted onto their retina. Although it restores only very rudimentary vision, the device has proved so successful that its developers are about to begin a study of a more sophisticated version on between 50 and 75 patients.

If this trial goes to plan, the device could be available to patients in two years and one day it could be used to digitally enhance human sight.

The bionic eye works by converting images from a tiny camera mounted on a pair of glasses into a grid of 16 electrical signals that transmit directly to the nerve endings in the retina.

“It’s amazing that even with 16 pixels how much our subjects have been able to do,” said Professor Mark Humayun at the Doheny Eye Institute at the University of Southern California who has pioneered the device.

“We were completely wrong...We thought from simulations that 16 would only give you distinction between light and dark and maybe some grey scale.”

In fact, subjects are able to tell the difference between objects such as a cup, a plate and a knife. They can also tell which direction objects are moving in front of them. “The brain is able to fill in a lot of the information,” he added.

One of Prof Humayun’s patients is Terry Byland, 58, from Corona, near Los Angeles. He used to sell power tools before going blind from a condition called retinitis pigmentosa in 1993.

And it has had a profound impact on his life. “I was with my son, walking, the first time - it was the first time I had seen him since he was five years old. I don’t mind saying, there were a few tears wept that day.”

The camera in the glasses sends a signal to a pocket device the size of a blackberry, which processes the images in real time into a four by four grid of electrical signals. This grid is then transmitted wirelessly to the eye implant, which converts these into signals sent directly to nerve endings in the retina.

In the current devices the receiver for the signal is implanted under the skin behind the ear with a wire connection to the eye implant, but the team have shrunk the electronics so the improved version fits under the skin around the eye.

More significantly, it now has 60 pixels instead of 16 and because it is smaller the operation to implant it is much less traumatic, taking just 90 minutes instead of eight hours. Prof Humayun predicts that it will cost around $30,000 (£15,400).

Developing the first device took 16 years of research, but the 60 pixel version has taken just four. The implant is not suitable for every form of blindness. If the optic nerve or vision processing centres in the brain are damaged it cannot help, but there are many conditions in which patients lose the function of the receptor cells in the retina and go blind, even though the neural circuitry behind is intact. ap

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