Research have developed an eye test based on pupil responses that they say is 92.5 per cent accurate in seperating children with autism from those who are developing normally.
Diagnosing autism can be a difficult task for a doctor so any tools they can use to aid the process will be welcome news. Diagnosis at a young age is particularly difficult but also of great importance to the outcome of treatment and the future of the child.
Current estimates suggest 1 in 150 children are now affected by autism but it remains poorly understood from a scientific and medical standpoint. There has much genetic research and a number of genes thought to be involved have been identified. However, genetics alone cannot account for the increasing incidence seen over past decades which has lead researchers to look for environmental causes such as chemical toxins, infections and allergens. It is now thought by many that interaction between genetic susceptibility and environmental exposures may trigger the developmental disorder.
What is known for certain is that early diagnosis and commencement of treatment leads to better outcomes for the child. Those who are diagnosed when they are older tend to respond less favourably to therapeutic interventions. With no biological tests available to doctors they must currently rely on knowledge of the condition and ability to spot symptoms and warning signs. The eye test developed by University of Missouri researchers may significantly enhance the ability of doctors to diagnose early.
The test is based on the finding that the pupils of autistic children respond more slowly to changes in light than those of their healthy counterparts. "No comprehensive study has been conducted previously to evaluate the pupils' responses to light change, or PLR, in children with autism," explains Gang Yao, associate professor of biological 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."
The study involved the use of a computerized binocular infrared device, something which opticians and ophthalmologists often use for vision tests. The researchers in this instance used the device to measure how the pupils of autistic and healthy children reacted to a 100-millisecond flash of light. This pupil reaction test reveals potential neurological dysfunction in areas of the brain that autism is thought to affect. The researchers found that pupils of children diagnosed with autism were significantly slower to respond than those of a control group of children who were developing normally.
"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."
In October Yao's team at the University of Missourri received a grant from the US National Institutes of Health (NIH) for the next phase of their research. In this study, the researchers hope to confirm the earlier study's findings with larger numbers of children and refine their techniques as well as looking for any link between PLR and a group of other medical conditions that could be associated with autism.
Source: Fan X Miles JH Takahashi N Yao G (2009) Abnormal Transient Pupillary Light Reflex in Individuals with Autism Spectrum Disorders Journal of Autism and Developmental Disorders 39(11):1499
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