Semi-Automated Score-Guided Optic Nerve Sheath Diameter Assessment

Ultrasound measurement of the optic nerve sheath diameter (ONSD) is a widely used non-invasive surrogate for intracranial pressure, yet its reliability is limited by measurement variability and observer dependence. In this study, we introduce a semi-automated, score-guided framework for ONSD assessment and evaluate its performance during acute hypoxia. Twelve healthy participants were exposed to 24 hours of normobaric hypoxia (FiO 13.1%) in a controlled environment, with images acquired at baseline, 6, 12, and 24 hours. Image sequences were quality-scored by two expert raters and processed using a semi-automated framework to extract quantitative metrics of sheath geometry. This included the conventional sheath diameter and new metrics such as thickness, curvature, and alignment. Across 44 datasets, ~54% achieved an expert quality score ≥3. These higher-rated images were associated with a modest but progressive increase in sheath width under hypoxia, whereas low-quality datasets showed inconsistent trends. Differences in ONSD change depended strongly on the depth at which measurements were taken. Several image-derived metrics, particularly visible sheath length, width, and thickness, correlated strongly with expert ratings, providing objective markers of quality. Together, these findings demonstrate that score-guided analysis improves diagnostic confidence and could strengthens the role of ONSD for intracranial pressure monitoring in critical care.