Linda M., a petite brunette in her early 60s (pictured at right), first realized that something was wrong with her vision when she couldn’t find things she dropped. An ophthalmologist soon confirmed her suspicions and delivered a sobering diagnosis: Linda was exhibiting the early signs of retinitis pigmentosa (RP), a disease that attacks cells in the retina and ultimately would destroy her vision, possibly within 10 years. She was only 21 at the time.
RP is a relatively rare, inherited disease that affects about one in four thousand people, and no treatments or cures are available. As in Linda’s experience, symptoms often begin in early adulthood with loss of peripheral vision and grow increasingly worse. Millions more become blinded each year due to age-related macular degeneration (AMD), which strikes the same photoreceptor cells in the retina.
Linda’s vision continued to deteriorate over the next 30 years, but her determination to go on with life’s normal activities, with the support of her husband Roy, allowed them to enjoy a full family life and raise three daughters. Linda lost her remaining vision in her early 50s and has been completely blind for about 10 years. She views her condition with the frustration of one whose nature is strong and independent. “It’s really irritating to rely on others,” she says.
Linda first heard about the DOE Artificial Retina Project from an ophthalmologist who thought she might be a good candidate for the study. Upon visiting the project leaders at the Doheny Eye Institute (University of Southern California), she learned that volunteers undergo a surgical procedure to implant a tiny array with 16 electrodes on the damaged retina of one eye. When activated later on, the electrodes would perform some of the light-signaling functions of the destroyed retinal cells, allowing the patient to see patterns of lights like a lit-up scoreboard. For 18 months post surgery, participants would return for weekly follow-up visits.
Linda understood that the retinal prosthesis could provide only a rudimentary form of sight, but even that was intriguing. She also thought that her participation in the study would allow researchers to learn more for future generations. “OK, let’s do it,” she told them. One week later, the Doheny Eye Institute surgeons performed the operation. It turned out to be “a breeze,” she said. “One night in the hospital, and I was on my merry way.”
Researchers speculate about what a patient with a retinal implant might see, but no one really knows how the brain of someone who has been blind for many years will process new visual input. For this reason, researchers and patients must work together to map the new world of artificial sight.
Two weeks after the surgery, doctors activated the device. Linda admits that her reaction upon first seeing the flashing lights coming from the implanted electrodes was, “I’m going to have to connect a lot of dots before I see anything.” But after several visits to the lab, she began to make some correlations between the patterns of lights and the physical world. A line of vertical lights, for example, could be a door or the edge of a table. With practice, the time needed to interpret the dot-images grew shorter. A year and a half after receiving the implant, she was given the go-ahead to try using the device at home.
Now, after almost 2 years with the implant, Linda and Roy reel off examples of how the implant has impacted their lives, including some unexpected ways. Mostly, it has helped Linda gain more control over her environment, as she negotiates more confidently around the house. “I see where the kitchen table and counters are, and I don’t knock glasses over anymore,” she reports.
She also needs less help in interpreting the outside world. When Linda and her husband go to church, she knows where the priest and choir sit. When someone approaches, she can turn to face them before they begin to speak. On their evening walks, she can tell whose porch lights are turned on, giving her some sense of location. Also, when riding on the freeway at night, she knows when they are passing through a tunnel or near a well-lit mall.
Linda becomes animated as she talks about attending her grandchildrens’ sporting events. “Now I can follow the action after my grandchild hits the ball in a Little League game,” she says with satisfaction.
She laughs as she reports that she also sees things she’d rather not. On a recent visit to Disneyland, Linda climbed into a fast ride with her grandchildren. As the speed ramped up, she automatically shut her eyes, only to discover that the external camera in the retinal prosthesis continued to provide visual input, sending signals to the brain. “Things were flashing much faster and closer than I liked,” she says. “I’ll know to turn it off the next time.”
Researchers at the Doheny Eye Institute say Linda’s experience and that of five other patients with implants is just the beginning of what they hope to provide for people with retinal diseases. A second, improved model with 60 electrodes is now in preclinical testing and soon will be implanted in a new group of volunteers. A third, vastly improved model containing hundreds of electrodes is now in early stages of development. The ultimate goal is to restore unaided mobility, facial recognition, and the ability to read large print. “If I’m still around then,” says Linda, “I’ll want one of those models. I’d do it again.”
Base URL: http://artificialretina.energy.gov
Last modified: Tuesday, May 15, 2018