Pupil Light Response Test May Screen for Autism in Kids
Author: Washington State University
Published: 2022/08/22 - Updated: 2026/01/28
Publication Type: Research, Study, Analysis
Category Topic: Autism - Related Publications
Page Content: Synopsis - Introduction - Main - Insights, Updates
Synopsis: This research from Washington State University demonstrates that measuring pupillary light reflex - how pupils respond to light - could provide an objective, noninvasive screening tool for autism spectrum disorder in young children. Published in Neurological Sciences, the study's credibility stems from rigorous clinical testing comparing 36 children with diagnosed autism to 24 typically developing children, revealing measurably slower pupil constriction and dilation speeds in autistic children. The findings are particularly valuable because current autism diagnosis relies heavily on subjective behavioral assessments, averaging four years of age in the U.S., while earlier intervention between 18-24 months significantly improves long-term outcomes. The portable monocular pupillometer device tested in actual clinical settings represents a practical advancement that could help pediatricians identify at-risk children sooner, potentially making the difference between verbal speech acquisition and remaining nonverbal for affected children - Disabled World (DW).
- Definition: Autism Spectrum Disorder (ASD)
Autism spectrum disorder (ASD) is a developmental disability caused by differences in the brain. Some people with ASD have a known difference, such as a genetic condition. Other causes are not yet known. People with ASD may behave, communicate, interact, and learn in ways that are different from most others. ASD begins before the age of 3 years and can last throughout a person's life, although symptoms may improve over time. The abilities of people with ASD vary significantly.
Introduction
Sensitivity and specificity of pupillary light reflex measures for ASD using monocular pupillometry
Measuring how the eyes' pupils change in response to light - known as the pupillary light reflex - could potentially be used to screen for autism in young children, according to a study conducted at Washington State University.
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, a disorder that affects communication and social interaction with others. Such a tool would allow health care providers to catch children earlier in their development when interventions are more likely to benefit them.
"We know that when we intervene as early as ages 18 to 24 months, it has a long-term impact on their outcomes," said Lynch, an assistant professor at the WSU Elson S. Floyd College of Medicine who worked with children with autism while practicing as a speech-language pathologist. "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 U.S., which is four years old."
Main Content
Published in the journal Neurological Sciences, the study tested 36 children aged 6 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. After removing the light, their pupils also took longer to return to their original size.
"What we did with this study is we demonstrated the parameters of interest that matter - 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."
An earlier study led by Lynch tested children in a laboratory using binocular pupillometry, which uses an expensive, stationary setup that measures both eyes simultaneously. The lower expense and portability associated with monocular technology made it possible to move testing into clinical settings similar to those in which the screening tool Lynch is developing might be used once it is commercially available.
Supported by funding from the Washington Research Foundation, Lynch is now working on expanding testing to a group of 300 or more 2 to 4-year-olds across a larger number of clinical sites. Data from that study will be used to validate the earlier findings. They will be integrated into the ultimate screening device to provide benchmark providers can use to decide whether or not to refer a child for evaluation. Meanwhile, Lynch is preparing to file for Food and Drug Administration premarket approval for the screening device through Appiture Biotechnologies, a spinoff company she cofounded to help move this technology from an academic research setting toward widespread use in pediatric clinics.
Lynch's desire to improve autism screening grew from her experiences watching parents struggle through the cumbersome process of pursuing a formal diagnosis for their child.
While an estimated one in 44 children in the U.S. is diagnosed with autism spectrum disorder (ASD) by age 8, many kids get misdiagnosed or missed altogether due to the subjective nature of the diagnostic process. A quick, objective screening method to bolster behavioral screening could help improve the accuracy and speed with which children are diagnosed. Looking at the pupillary light reflex as a potential screening biomarker made sense to Lynch, given her observations and earlier studies that found abnormalities in the pupillary light reflex of children with autism.
"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 straightforward, noninvasive measure to determine whether there were differences between typical development and autism."
Insights, Analysis, and Developments
Editorial Note: The significance of this pupillary light reflex research extends beyond its technical merit - it addresses a pressing healthcare gap where families often wait years navigating complex diagnostic processes while their children miss critical intervention windows. What makes this work particularly promising is its practical translation from laboratory to clinical settings using affordable, portable technology that frontline pediatricians could actually implement during routine checkups. As the research team expands testing to 300 children aged 2-4 and pursues FDA approval through their spinoff company, we're potentially witnessing the early stages of a transformative shift in autism screening. The biological basis for the test - cranial nerve function in the brainstem that also governs speech and language development - provides a logical foundation that connects observable physiological differences to the developmental challenges families observe in their children, offering hope for objective screening that complements rather than replaces behavioral assessment - Disabled World (DW).Attribution/Source(s): This quality-reviewed publication was selected for publishing by the editors of Disabled World (DW) due to its relevance to the disability community. Originally authored by Washington State University and published on 2022/08/22, this content may have been edited for style, clarity, or brevity.