A vision to behold - Macleans.ca

A vision to behold

New computer-based exercises help retrain the brain to see

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A vision to beholdRecovering from back surgery in a hospital bed, Millie Sauer, a self-confessed bookworm, pulled out a novel and began to read. She knew immediately that something was wrong. “Part of the page was grey. That had never happened before,” says Sauer, 69. The hospital did some tests, she says, “and discovered I’d had a stroke.”

Sauer struggled to cope with her partial loss of vision—one the doctors said was permanent. “I’d walk into the wall because I couldn’t see on the left side,” recalls Sauer, a retiree in Bismarck, N.D. Increasingly frustrated, she went online and found Krystel Huxlin, an associate professor at the University of Rochester Eye Institute. “When I got a hold of Krystel, things started looking up,” Sauer says.

Huxlin and her team recently made a stunning announcement: by doing a set of visual exercises on a computer, stroke patients suffering from partial blindness were able to regain some sight, offering hope for a condition that was once considered permanent. Indeed, computers are being used in novel ways to improve eyesight: in another study, video games were shown to actually boost vision in adults. Just as physical training can make a body stronger, visual training holds the potential to make us see better.

About one-quarter of stroke patients experience some vision loss, says Dr. Michael Hill, an associate professor at the University of Calgary’s Hotchkiss Brain Institute and spokesperson for the Heart and Stroke Foundation of Canada. After all, “you don’t see with your eyes,” he explains. “You see with your brain.” Information passes through the eyes to the primary visual cortex, the gateway through which it’s fed to other parts of the brain and then processed into an image. “If damage [from a stroke] occurs along a visual pathway, you can lose vision,” he says.

A stroke victim’s eyes, though, are often perfectly fine—and continue to receive information, even if the brain doesn’t know what to do with it. Huxlin’s goal was to recruit healthy regions of the brain to bring that visual information into consciousness.

In the study, Huxlin’s team recruited seven stroke victims, including Sauer, all of whom had suffered damage to the primary visual cortex. They were asked to stare at a small black square in the middle of a computer screen. Every few seconds, roughly 100 dots would appear within the patient’s damaged visual field—meaning they were initially invisible. Moving in a cluster across the screen, the dots would twinkle into sight, then disappear. The patient had to indicate if the dots moved left or right, with a chime indicating the correct answer, giving the brain positive feedback. Participants did these exercises once or twice a day for up to 18 months, spending as much as 30 minutes at a time.

This type of visual training, Huxlin says, was inspired by physiotherapy that improves patients’ motor skills after a stroke. “There’s nothing wrong with the visual system; we just didn’t know how to retrain it properly,” she says. “Now, we do.”

Huxlin isn’t the only researcher employing computers to improve patients’ eyesight. A separate study, also from the University of Rochester, showed video games can improve an adult’s vision. In the study, led by Daphne Bavelier, 35 students were asked to play 50 hours of video games over nine weeks one summer. One group played first-person-shooter games Call of Duty 2 and Unreal Tournament 2004; the other played The Sims 2, a richly visual game that doesn’t require the hand-eye coordination of the other two. By the end of the nine weeks, those who played shooter games showed a 43 per cent improvement in ability to discern close shades of grey (also known as contrast sensitivity, the main determinant of how well we see). The Sims players showed none.

Renjie Li is a U of R graduate student and co-author of the study. “Usually, laser eye surgery or eyeglasses are used to improve contrast sensitivity by changing the parameters of the eyeballs,” he says. “Video games don’t change your eyeballs, but they can change how your brain processes visual information.” Action video games like Call of Duty 2 feature unpredictable events; they’re fast-paced and require aiming skill, he explains. What’s more, motivation and reward are built in. By devoting hours at a time to playing games, Li explains, subjects’ brains learned how to process information more efficiently. Positive effects seemed to last up to a year.

Of course, computers aren’t uniformly good for our eyes—sitting in front of a screen all day can lead to eye strain. “But what we’re dealing with here is a bad brain, not bad eyes,” Huxlin says. “This is the only way we know to retrain the brain to see.” Huxlin hopes her treatment will become as widely available as physical rehab is today. “A lot of people just accept that there’s nothing that can be done [for stroke-induced blindness],” she says. “They shouldn’t have to.”

Those who participated in Huxlin’s study, Sauer included, managed to actually regain some of their lost eyesight. For Sauer, it made all the difference; she can even drive today, although she sticks to secondary roads, and still does the training every day. “I do have improvement in my vision; I can see it,” she says. “As long as it keeps getting better, I will keep doing it.”