Children with autism have slower pupil responses to light change: Study

Autism affects 1 in 150 children today, making it more common than childhood cancer, juvenile diabetes and pediatric AIDS combined. Despite its widespread effect, autism is not well understood and there are no objective medical tests to diagnose it. Recently, University of Missouri researchers have developed a pupil response test that is 92.5 percent accurate in separating children with autism from those with typical development. In the study, MU scientists found that children with autism have slower pupil responses to light change.

"No comprehensive study has been conducted previously to evaluate the pupils' responses to light change, or PLR, in children with autism," said Gang Yao, associate professor of biological engineering in the MU College of Agriculture, Food and Natural Resources and the College of Engineering. "In this study, we used a short light stimulus to induce pupil light reflexes in children under both dark and bright conditions. We found that children with autism showed significant differences in several PLR parameters compared to those with typical development."

In the study, scientists used a computerized binocular infrared device, which eye doctors normally use for vision tests, to measure how pupils react to a 100-millisecond flash light. A pupil reaction test reveals potential neurological disorders in areas of the brain that autism might affect. The results showed that pupils of children diagnosed with autism were significantly slower to respond than those of a control group.

"There are several potential mechanisms currently under study," Yao said. "If these results are successfully validated in a larger population, PLR response might be developed into a biomarker that could have clinical implications in early screening for risks of autism. Studies have shown that early intervention will improve these children's developmental outcome."

Yao's study, completed with Xiaofei Fan, post-doctoral fellow at MU, Judith Miles, professor and William S. Thompson Endowed Chair in Child Health, and Nicole Takahashi, senior research specialist at MU's Thompson Center for Autism and Neurological Disorders, has been published in the Journal of Autism and Developmental Disorders. In October, the scientists received a grant from the National Institutes of Health for the next phase. For this study, the researchers hope to amplify the earlier study's measurements and investigate any correlation between PLR and several other medical conditions that could be associated with autism.