Handheld monocular pupillometer offers promise for autism screening in young children

According to a study conducted at Washington State University, measuring the pupillary light reflex — the degree to which the pupils dilate in response to light — could potentially be used to screen young children for autism.

The proof-of-concept study, according to lead author Georgina Lynch, builds on previous research to support the continued development of a portable technology that could provide a quick and simple way to screen children for autism, a disorder that affects communication and social interaction. Such a tool would enable health care professionals to detect children’s developmental issues earlier, when interventions are more likely to be beneficial.

Lynch, an assistant professor at the WSU Elson S. Floyd College of Medicine who worked as a speech-language pathologist with children with autism, said, “We know that when we intervene as early as 18 to 24 months of age, it has a long-term effect on their outcomes.” “Intervention during this crucial period could determine whether or not a child acquires verbal speech or remains nonverbal. Despite 20 years of effort, the average age of diagnosis in the United States has not changed from four years.”

The study, which was published in the journal Neurological Sciences, compared 36 previously diagnosed autistic children aged 6 to 17 with a control group of 24 typically developing children. The pupillary light reflexes of children were evaluated by clinical professionals using a handheld monocular pupillometer, which measures one eye. In analysing the results, the researchers discovered that autistic children exhibited significant differences in the time it took for their pupils to constrict in response to light. In addition, it took longer for their pupils to return to their original size after the removal of light.

“With this study, we demonstrated the relevant parameters of interest, namely the rate of constriction and the return to baseline,” Lynch said. “And we demonstrated it using monocular technology because we knew there was no significant difference between eyes in terms of pupillary response in autism, unlike in cases of head trauma or concussion, in which unequal pupil sizes are common.

An earlier study led by Lynch examined children in the laboratory using binocular pupillometry, a costly, stationary instrument that measures both eyes. The lower cost and portability of monocular technology made it possible to move testing into clinical settings comparable to those in which Lynch’s soon-to-be-commercialized screening tool may be utilised.

Lynch is currently working to expand testing to include 300 or more 2- to 4-year-olds at a greater number of clinical sites, with support from the Washington Research Foundation. This study’s findings will be used to validate earlier findings and will be incorporated into the final screening device to provide a benchmark for providers to use when deciding whether or not to refer a child for evaluation. Lynch is preparing to file for Food and Drug Administration premarket approval for the screening device through Appiture Biotechnologies, a spin-off company she cofounded to facilitate the transition of this technology from an academic research environment to widespread use in paediatric clinics.

Lynch’s desire to improve autism screening was sparked by her observation of parents enduring a cumbersome process to obtain a formal diagnosis for their child.

While approximately 1 in 44 children in the United States are diagnosed with autism spectrum disorder (ASD) by age 8, due to the subjectivity of the diagnostic process, many children are misdiagnosed or missed entirely. Having a rapid, objective screening method to supplement behavioural screening could improve the diagnostic accuracy and speed of children. Lynch found it reasonable to consider the pupillary light reflex as a potential screening biomarker for autism, given her own observations and previous research demonstrating abnormalities in the pupillary light reflex of children with autism.

Even as a clinician, I observed children with ASD whose pupils were extremely dilated despite the presence of bright light. This system is modulated in the brain by cranial nerves originating from the brainstem, and adjacent cranial nerves influence your ability to learn speech and language. The pupillary light reflex is a test of the system’s integrity, so it made sense to use this very simple, noninvasive method to determine if there were differences between typical development and autism.”


Journal reference:

Lynch, G.T.F., et al. (2022) Sensitivity and specificity of pupillary light reflex measures for ASD using monocular pupillometry. Neurological Sciences. doi.org/10.1007/s10072-022-05976-2.

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