An Eye on Survival: Association Between Initial Optic Nerve Sheath Diameter and 30-Day Mortality in Patients With Traumatic Brain Injury.

Background Traumatic brain injury (TBI) is a major cause of morbidity and mortality worldwide, necessitating early identification of high-risk patients for timely management. Elevated intracranial pressure (ICP) is associated with poor outcomes in TBI, and optic nerve sheath diameter (ONSD), measured by bedside ultrasonography, has emerged as a useful noninvasive marker of elevated ICP. This study aimed to evaluate the association between initial ONSD measurement and 30-day mortality among patients with TBI. Methods A prospective observational study was conducted over one year in the Department of Emergency Medicine at Rajiv Gandhi Government General Hospital, Chennai, India. Sixty adult patients with clinically and radiologically confirmed TBI were included in the study. Patients with pre-existing intracranial or ocular pathology, direct ocular trauma, or delayed presentation beyond 48 hours were excluded. ONSD was measured in both eyes using bedside ultrasonography (MINDRAY system; Mindray Medical International Ltd., Shenzhen, China), and the mean value was recorded. Patients were followed for 30 days, and outcomes, including mortality, ICU stay, and duration of hospital stay, were documented. Statistical analysis included the chi-square test, independent t-test, analysis of variance (ANOVA), and receiver operating characteristic (ROC) curve analysis. Results The mean ONSD among study participants was 4.16 ± 0.70 mm. Fourteen patients (23.3%) died within 30 days, while 46 patients (76.7%) survived and were discharged. Mean ONSD was significantly higher among patients who expired compared to survivors (4.52 mm vs. 4.05 mm; 95% CI, p = 0.027). ROC analysis demonstrated an area under the curve (AUC) of 0.682 (95% CI: 0.549-0.796). An ONSD cut-off value >3.9 mm yielded a sensitivity of 78.57% and a specificity of 64.35% for identifying patients who experienced 30-day mortality. Increased ONSD was also significantly associated with lower Glasgow Coma Scale (GCS) scores, prolonged ICU stay, and longer hospital stay (95% CI, p = 0.001). Conclusion Initial ONSD measurement was significantly associated with injury severity and 30-day mortality in patients with TBI, supporting its potential role as an adjunct bedside marker for early risk stratification. Elevated ONSD was significantly associated with poorer neurological status and prolonged hospitalization, suggesting that bedside ONSD ultrasonography may serve as a useful non-invasive prognostic tool in emergency settings.