Ultrasound Assessment of Optic Nerve Sheath Diameter versus Fundus Examinationin Patients with Increased Intracranial Pressure

Aim: This study aimed to evaluate the diagnostic accuracy of ultrasonographic ONSD measurement compared with fundus examination in detecting elevated ICP among ICU patients. Methods: A cross-sectional study was conducted at Al-Azhar University Hospital, Damietta, between May 2024 and June 2025, including 65 adult patients (>18 years) with suspected increased ICP due to traumatic brain injury, intracranial hemorrhage, tumors, metabolic encephalopathies, or electrolyte disturbances. Patients with ocular conditions interfering with fundus assessment were excluded. All participants underwent clinical evaluation, non-contrast CT brain, lumbar puncture for direct ICP measurement, fundus examination, and ONSD ultrasonography. ONSD was measured 3 mm behind the globe in transverse and longitudinal planes. Diagnostic performance was analyzed using receiver operating characteristic (ROC) curves. Results: The study population had a mean age of 49.8 ± 13.4 years, with a male predominance (60%). Hypertension, diabetes, and renal disease were the most common comorbidities. Major etiologies included intracranial tumors (24.6%), hemorrhage (16.9%), and head trauma (15.4%). ROC analysis identified an ONSD cutoff of 5.205 mm for elevated ICP, yielding a sensitivity of 86.7%, specificity of 94.3%, positive predictive value of 92.9%, and negative predictive value of 89.2%. The area under the curve was 0.973 (p < 0.001), indicating excellent diagnostic accuracy. Conclusion: Ultrasonographic ONSD measurement is a reliable, non-invasive, and highly accurate bedside method for detecting elevated ICP in critically ill patients, offering a valuable adjunct to conventional assessment tools.