<p>ONSD and associated parameters ROC.</p>

<div> <p>Objective</p><p>This study aims to find a quick bedside ultrasonography evaluation technique that evaluates the optic nerve sheath diameter to eyeball transverse diameter (ONSD/ETD) ratio and middle cerebral artery (MCA) flow parameters at 6 hours post-return of spontaneous circulation (ROSC) for early neurological prognosis.</p> <p>Methods</p><p>This retrospective study included 49 patients who achieved return of spontaneous circulation (ROSC) and were admitted to our emergency department between September 2023 and September 2025.

Collected data encompassed baseline characteristics, GCS-M scores, APACHE-II scores, and bedside ultrasound measurements of ONSD, ONSD/ETD at 6, 24, and 48 hours post‑ROSC and middle cerebral artery hemodynamic parameters at 6, 24 hours post‑ROSC. The statistical analyses included the Mann-Whitney U test, t-test, and Receiver Operating Characteristic (ROC) curve analysis.</p> <p>Results</p><p>The ONSD/ETD ratio at 6 hours post-ROSC was a robust predictor of unfavorable neurological outcomes (AUC 0.922, <i>P</i> = 0.001), outperforming ONSD alone (AUC 0.866, <i>P</i> = 0.003), with an optimum threshold of 0.256 (sensitivity 76.5%, specificity 100%).