A study conducted by scientists at Washington State University (WSU) states that measuring how the pupils of the eyes change in reaction to light, known as the pupillary light reflex, could be used to screen early infants for autism. First author Georgina Lynch said the proof-of-concept study builds on earlier work to support the continued development of a portable technology that could provide a quick and easy way to screen children for autism.
Assistant professor in WSU, Lynch said, “We know that when we intervene as early as ages 18 to 24 months it has a long-term impact on their outcomes. Intervening during that critical window could be the difference between a child acquiring verbal speech and staying nonverbal. Yet, after 20 years of trying we still have not changed the average age of diagnosis here in the US, which is four years old.”
Published in the journal Neurological Sciences, the study tested 36 children aged six to 17 who had been previously diagnosed with autism along with a group of 24 typically developing children who served as controls. Children's pupillary light reflexes were tested by trained clinical providers using a handheld monocular pupillometer device, which measures one eye at a time. Analyzing the results, the researchers found that children with autism showed significant differences in the time it took for their pupils to constrict in response to light. Their pupils also took longer to return to their original size after the light was removed.
"What we did with this study is we demonstrated the parameters of interest that matter- the speed of constriction and return to baseline," Lynch said. "And we demonstrated it with monocular technology because we knew there is no significant difference between eyes in terms of the pupillary response in autism, unlike in head injury or concussion where it's common to see unequal pupil sizes.
"Even as a clinician, I noticed this state in kids with ASD where their pupils were very dilated even in the presence of bright light," Lynch said. "That system is modulated in the brain by cranial nerves rooted in the brainstem, and adjacent cranial nerves affect your ability to acquire speech and language. The pupillary light reflex tests the integrity of that system, so it seemed logical to try this very simple, noninvasive measure to determine whether there were differences between typical development and autism.”
