Interventions in adulthood can improve binocular disorders
For years, clinicians thought that once a patient passed the age of about 8, the opportunity to correct binocular vision disorders might be lost. A recent clinical report published in Optometry and Vision Science has found that substantial improvements can be made well into adulthood, and stereovision can be achieved even after years of living with binocular disorders.
Stereopsis is the optimal state of vision, in which the brain can reconcile the visual information from both eyes and translate it into three-dimensional structures and an accurate perception of depth. A 2001 study estimated that up to 56% of 18- to 38-year-olds live with some dysfunction that keeps them from achieving full stereopsis. Amblyopia and strabismus are the two most common conditions that cause this type of stereodeficiency, which manifests as two-dimensional vision in a 3-D world.
In this report, researchers polled patients who achieved stereopsis as adults. Most had suffered from strabismus or amblyopia for as long as they could remember. Of those polled, 90% reached stereopsis through vision therapy or a combination of vision therapy and surgery.
"I think this is great. We now have so much evidence to conclude that the brain is very plastic, even in adulthood," says Ida Chung, O.D., assistant dean of learning and associate professor at the Western University College of Optometry in Pomona, California. "Here are some real-life stories of individuals who received vision training and had a change in their quality of life."
Dr. Chung points out that the report describes the improved vision as "vivid." She thinks it's an apt description for someone who previously had difficulty determining whether branches extended from the trunk of a tree or a car steering wheel jutted out from the dashboard.
Some of the subjects in the poll underwent surgery, but all of them received vision therapy. Vision therapy is typically conducted for an hour a week in a doctor of optometry's office, with some home-based activities between sessions. The potential for improving quality of life needs more study but continues to look bright. Will there be a day when vision therapy is as de rigueur as brushing your teeth?
Probably, says Dr. Chung.
"It depends on what your goals are. For some people, it's about rehabilitation, getting back to normal functioning, like these individuals in the report who have stereodeficiency. And then some individuals, like athletes, for example, have vision that is working pretty normally, but they want to be even better."
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