Optic nerve sheath diameter (ONSD) is a potential surrogate measure of intracranial pressure (ICP) that can be measured quickly on computed tomography (CT) scan to triage patients who may require more invasive monitoring of ICP.
Why this matters
Increased ICP following acute neurological injury is associated with increased risk of morbidity and mortality. However, the current standard for assessing increased ICP involves insertion of a catheter, which risks hemorrhage and infection.
The optic nerve sheath is an extension of the dura mater and subarachnoid space and therefore affected by changes in ICP. If changes in ONSD could be detected on CT scan, this could provide a more effective and less invasive way to identify patients with increased ICP.