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June 15, 2009

Eyesight to the Blind


Artificial retinas give hope for restoring sight

We met Kathy Blake while she was taking a stroll in the park...by herself. What's so striking about this is that Kathy is completely blind, and has been for over 30 years now.

The diagnosis from her doctor: Retinitis pigmentosa, or RP. It's a genetic disease that leads to progressive visual loss and is not curable. Photoreceptive cells in the retina slowly start to die leaving the patient visually impaired.

"Life was great the year right before I was diagnosed," Kathy said. "I had just started a new job, I just bought my first new car. I had just started dating my now husband. And, life was good. And then, the doctor had told me that there was some good news and some bad news."

"'The bad news is you are going to lose your vision, the good news is we don't think you are going to go totally blind.' Unfortunately, I did lose all my vision within about 15 years."

Glimmer of hope

Two years ago, Kathy got a glimmer of hope. She heard about an artificial retina being developed by a company called Second Sight and the Doheny Eye Institute in Los Angeles. It was experimental, but Kathy was the perfect candidate.

Dr. Mark Humayun is a retinal surgeon and biomedical engineer at Doheny. "A good candidate for the artificial retina device is a person who is blind because of retinal blindness," he said. "They've lost the rods and cones, the light sensing cells of the eye, but the rest of the circuitry is relatively intact. In the simplest rendition, this device basically takes a blind person and hooks them up to a camera."

It may sound like the stuff of science fiction...and just a few years ago it was. A camera is built in to a pair of glasses, sending radio signals to a tiny chip in the back of the retina. The chip, small enough to fit on a finger tip, is implanted surgically and stimulates nerves that lead to the vision center of the brain. Kathy is one of twenty patients who have undergone surgery and use this device.

Testing the implant

It's been about two years since the surgery, and Kathy still comes for weekly testing at the University of Southern California's medical campus.

Kathy scans back and forth with specially made, camera-equipped glasses until she senses the objects on the screen and then touches them.

The low resolution image from the camera is still enough to make out the black stripes on this board. Impulses are sent from the camera to the 60 receptors that are on the chip in her retina. So, what is Kathy seeing?

"I see flashes of light that indicate a contrast from light to dark. The flashes are now starting to make a little more sense to me where, if there is a line, that I am actually kind of seeing the flash in a line instead of just a flash on and off. Very similar to a camera flash, probably not quite as bright because it's not hurting my eye at all," she replied.

Period of Adjustment

Humayun underscored what a breakthrough this is, and how a patient adjusts. "If you've been blind for 30 or 50 years, all of a sudden you get this device, there is a period of learning," he said. "Your brain needs to learn. And it's literally like seeing a baby crawl--to a child walk--to an adult run."

While hardly perfect, the device works best in bright light or where there is a lot of contrast. Kathy takes the device home. The software that runs the device can be upgraded. So, as the software is upgraded, her vision improves. Recently, she was outside with her husband on a moonlit night and saw something she hadn't seen for a long time.

"I scanned up in the sky (and) I got a big flash, right where the moon was, and pointed it out. I said, 'There's a big flash right there' and he said, 'That's it!' I can't even remember how many years ago it's been that I would have ever been able to do that."

A future that's even brighter

This technology has a bright future. The current chip has a resolution of 60 pixels. Humayun says that number could be increased to over a thousand in the next version.

"I think it will be extremely exciting if they can recognize their loved ones' faces and be able to see what their wife or husband or their grandchildren look like, which they haven't seen," said Humayun.

Kathy dreams of a day when blindness like hers will be a distant memory. "My eye disease is hereditary," she said. "My three daughters happen to be fine, but I want to know that if my grandchildren ever have a problem, that somewhere down the line, they will have something to give them some vision."

Kathy Blake is taking the first small steps to make that vision a reality.

Miles O'Brien, Science Nation Correspondent
Jon Baime, Science Nation Producer


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