Exercises counteract lazy eye

Science News,  March 15, 2008  by Nathan Seppa

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An innovative set of eye exercises enables people with amblyopia, or lazy eye, to improve their vision, researchers report.

Amblyopia stems from a youthful eye injury, disease, or defect that induces the brain to "give up" on signals from that eye. A patch over the good eye can reprogram the brain before the age ors. Otherwise, the brain will remain hardwired to disregard input from the weak eye, scientists have thought. That assumption has come under fire in recent years (SN: 5/14/05, p. 317).

Using a set of tasks devised by scientists at Beijing Hospital in China, Zhong-Lin Lu of the University of Southern California in Los Angeles and his colleagues tested 31 teenagers and young adults--10 with amblyopia and 21 with normal vision.

In the test, each participant looks at a screen and focuses on alternating black and white undulating waves. Upon hearing cues, amblyopia participants attempt to see the lines with the lazy eye, repeating this visual task 900 times each day. Sometimes the lines are within the person's capability, sometimes just beyond it, says Lu, a neuroscientist. "If they are doing too well and getting it 100 percent right, we reduce the contrast to make it harder for them," he says. The volunteers completed 9 to 12 daily sessions of the exercises.

While vision in the control group improved only slightly, the amblyopia patients gained two to three rows on a standard eye chart, the researchers report in the March 11 Proceedings of the National Academy of Sciences.

Lu notes that the vision improvements translated to everyday life and have lasted a year so far.

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