Early detection of a severe autism spectrum disorder group in young children using eye-tracking measures.

Delays in diagnostic confirmation remain common in young children with autism spectrum disorder (ASD). These delays are particularly concerning for children with severe symptoms and elevated support needs, for whom early identification is especially important. There is therefore a need for objective and feasible approaches to assist early identification prior to specialist evaluation. Eye-tracking is a non-invasive method for quantifying gaze-fixation patterns associated with ASD. The present study examined whether gaze-fixation indices derived from the Gazefinder eye-tracking system can identify a clinically defined severe ASD subgroup within a real-world clinical population. The analysis included 442 children aged 2-6 years referred to a child psychiatry outpatient clinic who underwent Gazefinder assessment. Based on Childhood Autism Rating Scale (CARS) scores, children were classified into a Severe ASD group (n = 42) and an Other group (Non-ASD and Mild-to-moderate ASD; n = 400). Gaze fixation rates on predefined regions of interest were compared, and discriminative performance was evaluated using receiver operating characteristic analyses. Children in the Severe ASD group exhibited reduced fixation on the mouth region in dynamic facial stimuli and reduced fixation on people relative to geometry. A composite criterion derived from four gaze-fixation indices yielded a sensitivity of 85.7% and a specificity of 55.3% for discriminating Severe ASD. These findings suggest that Gazefinder-based measures may provide adjunctive information to support screening and referral-related decision-making for clinically defined severe ASD in young children.