Autism affects an estimated 1 in 150 children but there are still no objective medical tests to diagnose it. Researchers at the University of Missouri have been looking at the way children's pupils respond to light. Pupils dilate (widen) when it is dark so more light reaches the retina and contract in bright light to prevent damage. The researchers found that the autistic children's pupils responded significantly more slowly than other children's and a test of pupil reaction time was 92.5% accurate in separating children from autism from other children.
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