A PROMISING THERAPY is offering hope to patients who have been left partially blind by a stroke. The approach is predicated on a revolution sweeping the field of neurobiology: the discovery that the adult brain isn’t fixed and immutable as once thought, but rather has the ability to “rewire” itself. The new treatment, called vision-replacement therapy, or VRT, aims to train healthy brain neurons to perform the function of those damaged or destroyed by a stroke.
About 10% to 15% of stroke victims— there are 700,000 every year in the U.S.— lose some or all of their vision. Strokes can damage the neurons, or brain cells, responsible for sight. As a result, the brain can no longer process visual signals, leaving patients with debilitating blank spots in their field of vision.
The vision therapy is one of the first to exploit the brain’s rewiring capabilities, known as neuroplasticity, though the notion holds promise for treating a number of conditions such as stroke induced paralysis or obsessive-compulsive disorder. For decades scientists had thought that the brain undergoes very little change after childhood. They knew the adult brain could form the new connections that underlie learning and memory, but believed that its basic structure was immutable and fixed, or “hard wired.”
That was why, scientists thought, young children are much better able to learn a second language or a musical instrument than adults are. And that was why physicians doubted that any therapy could restore sight after a stroke had knocked out something so fundamental as the brain’s visual system. The prognosis for stroke-impaired vision was even worse than for the partial paralysis from a stroke.
But early results from VRT are encouraging. In a paper being presented this week at the International Stroke Conference in New Orleans, researchers at the University of Magdeburg, Germany, say that in a small study, one-third of VRT patients had modest but noticeable improvement, and one-third had strong improvement. In a few cases, the entire blind spot disappeared. One-third of the patients in the study had no improvement in their vision. Participants were followed for three years after treatment and the results were found to be lasting, according to lead researcher, Bernhard Sabel.
Dr. Sabel helped form a closely held company, NovaVision, headquartered in Boca Raton, Fla., to offer the therapy, which received approval from the U.S. Food and Drug Administration in 2003. Clinics began offering it commercially last year. Today, seven clinics, including the Neurological Institute of New York at Columbia University Medical Center and Emory Eye Center in Atlanta, Ga., offer it. The six-month regimen averages around $6,000 and isn’t currently covered by insurance.
Alexander Furlan began VRT late last year. The 62-year-old former auto mechanic and ironworker—he helped build the World Trade Center—was watching television in the basement of his Connecticut home late one night in January 2003 when he suffered a stroke. “Everything went black,” he recalls. “I couldn’t move my left hand to work the remote control. My wife found me lying there at 8 the next morning.”
He spent three months in the hospital, his entire left side paralyzed. Occupational therapy at a unit of Danbury (Connecticut) Hospital has restored his ability to walk, albeit with a cane. But the stroke destroyed neurons in the left temporal region of his brain. As a result he has been unable to see anything in the top left quadrant of the visual field.
Settling his chin into the black plastic frame in front of the computer screen, he stares at the green dot in the center. It takes all his willpower to keep his eyes glued to this “fixation point,” resisting the urge to let them wander to white dots that suddenly pop onto the screen. When he sees a white dot with his peripheral vision, he clicks the mouse, causing a tone to sound: Got one. At random intervals, the central green dot changes color, to test if his eyes are straying. When it does, he clicks the mouse and another tone sounds. Score.
“The idea is to stimulate his peripheral vision around the blind spot, focusing on the border zone between the damaged neurons and the healthy ones,” says Columbia’s Randolph Marshall, Mr. Furlan’s neurologist. “By recruiting neurons immediately adjacent to the lesion” to perform the function of the stroke-damaged ones, “we hope to expand his peripheral vision.”
Mr. Furlan practices at home twice a day for 20 minutes per session, and visits Dr. Marshall regularly. After one month of therapy, a brain scan shows progress: “Some neurons on the periphery of the blind spot are already starting to move,” Dr. Marshall says.
Brain-based stroke therapies have been slow to catch on in the rehabilitation community. “There is a certain fatalism with lost vision, even worse than there is with lost speech or lost mobility,” says one neurologist who has long been frustrated by the resistance. According to neuroscientist Leonardo Cohen of the National Institute of Neurological Disorders & Stroke, “Very few of the basic scientific discoveries about neuroplasticity have moved into the clinic. But . . . the future is going to look a little brighter.”
VRT had its genesis in the mid-1990s, when neuroscientist Dr. Sabel began to wonder about patients he had heard about who spontaneously regained part of their vision lost to stroke. The reason, he suspected, lay in what neuroscientists were beginning to discover about the brains of lab animals: that the brain can take a region that had been “zoned” for one purpose and shift it to a different one. He developed a computer-based therapy that is the basis for the VRT Mr. Furlan is now using. The white dots pop up where they can be seen only by neurons in the patient’s “transition zone,” adjacent to those injured by stroke. The fixation point keeps the patient’s eyes from darting around, insuring that they see the white dots only with neurons next to those damaged by the stroke.
Dr. Sabel had a hunch that if these “transition zone” neurons were activated often enough—as they are when patients see the dots in their peripheral vision they would be re-trained to do the job of the injured neurons.
In 1998, in an early experiment reported in the journal Nature Medicine, Dr. Sabel and his colleagues showed for the first time that this repeated, targeted stimulation can substantially restore sight. The patients’ visual field—the amount of the space in front of them they’re able to see—expanded by about five degrees. Although that sounds small, it equals an area about the size of a 4×6 notecard held at arm’s length.
“The age of the patient makes no difference, and neither does the age of the lesion,” said Dr. Sabel. “If the stroke occurred one year ago or 10 or 35, we think the patient can still profit.”