Porcine study supports CLOSED optic nerve ultrasound protocol

Ultrasound measurements of the optic nerve and its sheath in pigs tracked closely with MRI in a new in-vivo porcine study, adding validation for the CLOSED ultrasound protocol as a standardized, non-invasive way to assess these structures. The study’s premise is clinically relevant because optic nerve sheath diameter is widely investigated as a surrogate marker for intracranial pressure, and prior animal work in pigs has also shown a linear relationship between ultrasound-measured optic nerve sheath diameter and intracranial pressure. The CLOSED protocol itself was developed to standardize optic nerve sheath sonography, including landmarking and safety-focused technique, and later human work used measurements taken 3 mm behind the optic disc in bilateral transverse and sagittal planes. (pubmed.ncbi.nlm.nih.gov)

Why it matters: For veterinary professionals, this is less about an immediately practice-ready ICP test and more about method validation. MRI is more anatomically definitive but less accessible, while ocular ultrasound is bedside, repeatable, and lower cost. A porcine in-vivo model that shows good agreement between ultrasound and MRI helps strengthen the technical foundation for future translational work in veterinary neurology, emergency, critical care, and research settings. That matters because veterinary literature in dogs, cats, and horses has already been exploring optic nerve sheath measurement as an indirect intracranial pressure marker, but standardization and species-specific reference work remain limiting factors. (journals.sagepub.com)

What to watch: The next step is whether this protocol moves from anatomic agreement studies into prospective veterinary studies that test diagnostic cutoffs, repeatability, and clinical decision-making in dogs, cats, and other patients with suspected intracranial hypertension. (pubmed.ncbi.nlm.nih.gov)