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Now to some of the latest medical advances in restoring eyesight. Millions of people in the U.S. have lost the ability to see from diseases that attack the retina. Now, scientists say they have brought back some vision in people with retinal damage. One team did it using stem cells, another using electronics.

NPR's Jon Hamilton has this story on research by both of those teams. It was presented in Chicago today at the annual meeting of the Society for Neuroscience.

JON HAMILTON: Doctors have gotten pretty good at fixing problems with the cornea, where light enters the eye, and they're experts at replacing the lens, which focuses that light. But it's a different story with the retina, a layer of cells at the back of the eye that transforms images of the world into nerve impulses.

Robert Aramant of the University of California-Irvine says a patient with retinal damage doesn't have many options.

Dr. ROBERT ARAMANT (University of California-Irvine): That is so terrible. A doctor can only say that you will probably be more and more blind, and you might be totally blind in 10, 15 years.

HAMILTON: Since the 1980s, Aramant has been part of a team working to fix retinas damaged by diseases, including macular degeneration and retinitis pigmentosa. And for several years now, the team has been treating patients using fetal retinal cells. Their approach is to retrieve an intact sheet of retinal cells and transplant that sheet into a damaged eye.

Dr. ARAMANT: And these cells develop later on to the layers of a normal retina.

HAMILTON: Aramant says they've treated just 10 patients so far because of funding constraints, but he says seven of those patients got better, including one woman whose vision went from 20/800, which is nearly blind, to 20/200, which is good enough to do most daily tasks.

Dr. ARAMANT: And she improved her life considerably. She actually could play a computer game, and she could write emails. She could write big letters of Reader's Digest, and she took up her hobby to paint ceramics.

HAMILTON: A very different approach to restoring vision comes from scientists at a California firm called Second Sight Medical Products. Brian Mech, a vice president with a PhD in material science, says the company has created a sort of bionic eye.

Mr. BRIAN MECH (Vice President, Second Sight Medical Products): The subject wears a pair of glasses that has a video camera in them, and then we wirelessly transmit the video signal to an implant that sits on the eye, and that implant then talks to an array of electrodes that are inside the eye on the retina.

HAMILTON: Those electrodes do what the old retina can't anymore: send electrical signals to the brain that allow sight. You can see an animation of how the device works at npr.org.

Mech says it usually takes patients' brains a while to make sense of the new signals.

Mr. MECH: They learn to use the device better over time so that someone that's had it for a year will do better than they did at three months.

HAMILTON: The artificial eye replaces millions of retinal cells with just 60 electrodes. Mech says that means vision is rudimentary.

Mr. MECH: A very large percentage of people can find doors and move towards them, and similarly, a large number can follow a line on a floor.

HAMILTON: Mech says patients tend to get emotional when they realize they can see even a little bit.

Mr. MECH: A lot of crying, a lot of smiling. You know, it's a sensory input that they haven't had in a very long time, and so they're excited.

HAMILTON: At the neuroscience meeting in Chicago, Second Sight presented a study showing that patients could tell which direction an object was moving. Also at the meeting, scientists presented studies showing ways to create new, light-sensitive molecules in the eye and how to use stem cells to grow specific types of retinal cells.

Jon Hamilton, NPR News.

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