EYE-TRACKING AS A DIAGNOSTIC TOOL FOR DYSLEXIA ADHD STROKE AND ALZHEIMER’S USING AVERAGE FIXATION DURATION METRICS

This study explores the utility of Average Fixation Duration (AFD)—the mean time a viewer’s gaze remains on a specific point—as a diagnostic biomarker across three distinct clinical populations: children with developmental dyslexia, stroke survivors with acquired dyslexia, and patients with Alzheimer’s disease. The authors argue that AFD provides a quantifiable, accessible metric for assessing cognitive load, attentional filtering, and motor-planning circuits, which can be easily calculated using standard software like Microsoft Excel.

The researchers utilized eye-tracking data exported from the Open Gaze and Mouse Analyzer (OGAMA) to calculate AFD across various Areas of Interest (AOIs). By comparing these values against established normative thresholds, the authors developed a framework to interpret gaze behavior. The study includes two longitudinal case studies: an 8-year-old child with developmental dyslexia and a 58-year-old stroke survivor. These cases demonstrate how AFD changes in response to targeted interventions, such as phonics-based reading instruction and visual scanning therapy.

The study identifies distinct AFD patterns for different conditions. Children with developmental dyslexia exhibit prolonged fixations (>550 ms) due to decoding difficulties, while children with ADHD show shorter, erratic fixations (<250 ms) reflecting impulsivity. Stroke survivors often display significantly elevated AFD (>800 ms) in contralesional visual fields, indicating spatial neglect. In Alzheimer’s patients, prolonged fixations (>600 ms) suggest a breakdown in attentional filtering and executive control. Crucially, the case studies show that effective therapy leads to a measurable reduction in AFD, suggesting that this metric is sensitive enough to track rehabilitation progress.