Abstract: Objective To explore the effectiveness and feasibility of transorbital ultrasound measurement of optic nerve sheath diameter (ONSD) in the early diagnosis of increased intracranial pressure (ICP) in elderly patients with critical neurological disease. Methods A total of 122 patients with neurocritical diseases who underwent continuous ICP monitoring after surgery and were admitted to the Geriatric Intensive Care Unit (ICU) and Geriatric ICU 2 ward of Jiangsu Province Hospital from August 2022 to August 2024 were selected. General information such as age, gender, primary disease, and Glasgow Coma Scale (GCS) score of the patients was collected.All the patients were divided into a non-elderly group (＜60 years old, 60 cases) and an elderly group (≥60 years old, 62 cases) by age, and into a male group (66 cases) and a female group (56 cases) by gender. All patients underwent implantation of an invasive ICP monitoring probe via the lateral ventricle during the operation to monitor ICP. ONSD at 3 mm behind the eyeball was measured by transorbital ultrasound. The optimal cut-off value of ONSD for diagnosing increased ICP was analyzed by receiver operating characteristic(ROC) curve, and the sensitivity and specificity were calculated. Results A significant positive correlation was observed between ONSD and ICP in both the non-elderly group, the elderly group, and the overall patient cohort (r=0.905, 0.909, 0.907, respectively, all P<0.01). Additionally, the scatter plot indicated a quadratic relationship between ONSD and ICP. As ICP levels increased, ONSD exhibited a non-linear growth trend characterized by an initial rapid expansion followed by a subsequent plateauing. There was a statistically significant difference in ONSD between male and female patients (P<0.01). ROC curve analysis showed that the optimal cut-off value of ONSD for diagnosing increased ICP (ICP≥20 mmHg) was 5.365 mm in male patients with a sensitivity of 0.933, and a specificity of 0.923; In female patients, the optimal ONSD cut-off value was 4.950 mm, with a sensitivity of 0.934 and a specificity of 0.938. Conclusions ONSD increases with ICP, but their relationship is quadratic; The optimal critical value for diagnosing ICP elevation by ONSD varies among patients of different genders, but it is not related to age. Bedside transorbital ultrasound measurement of ONSD can well determine the changes in ICP and has high clinical application value, which is worthy of promotion.

Key words: optic nerve sheath diameter, bedside ultrasound, intracranial pressure, correlation