A longitudinal study of pupillary light reflex in 6- to 24-month children.

Pupillary light reflex (PLR) is an involuntary response where the pupil size changes with luminance. Studies have shown that PLR response was altered in children with autism spectrum disorders (ASDs) and other neurological disorders. However, PLR in infants and toddlers is still understudied. We conducted a longitudinal study to investigate PLR in children of 6-24 months using a remote pupillography device. The participants are categorized into two groups. The 'high risk' (HR) group includes children with one or more siblings diagnosed with ASDs; whereas the 'low risk' (LR) group includes children without an ASD diagnosis in the family history. The participants' PLR was measured every six months until the age of 24 months. The results indicated a significant age effect in multiple PLR parameters including resting pupil radius, minimal pupil radius, relative constriction, latency, and response time. In addition, the HR group had a significantly larger resting and minimal pupil size than the LR group. The experimental data acquired in this study revealed not only general age-related PLR changes in infants and toddlers, but also different PLRs in children with a higher risk of ASD.

Atypical pupillary light reflex in 2-6-year-old children with autism spectrum disorders.

The purpose of this study was to investigate pupillary light reflex (PLR) in 2-6-years-old children with autism spectrum disorders (ASD). A total of 117 medication-free 2-6-year-old boys participated in this study. Sixty participants were diagnosed with ASD (the "ASD group") and the other 57 were in the control group of typical development (the "TD group"). A questionnaire was completed by the parent/guardian for assessing potential dysfunctions in the autonomic nervous system (ANS). The base pupil radius, PLR latency, and constriction time showed a significant age-related trend in both the ASD and TD groups. The base pupil size increased with age in the typically developing children, but not in the ASD group. The ASD group showed more symptoms related to ANS dysfunctions. An association between abnormal sweating with base pupil radius and PLR constriction was observed in the TD group but not the ASD group. The different association of PLR parameters with ANS dysfunction may suggest disrupted autonomic controls in children with ASD. Autism Res 2017, 10: 829-838. © 2017 International Society for Autism Research, Wiley Periodicals, Inc.

rPLR: an imaging system for measuring pupillary light reflex at a distance.

Pupillary light reflex (PLR) is a simple noninvasive neurological test that can reveal a great amount of information of the neural system. We report here a novel imaging system for measuring PLR without using any restraints to limit the subject's movement. Our system incorporates a tracking component that can locate the subject's eye position and redirect the pupillary imaging component to follow the subject's movement. This system can measure PLR, at a distance from the subject, with high spatial resolution (<50 µm) and temporal resolution (120 Hz). Because this new PLR device can accommodate the subject's movement, it is well positioned to test in young children and other people who have difficulty remaining voluntarily still during tests.