Neuroimaging in neuro-ophthalmologic emergencies with acute visual loss

Neuro-ophthalmologic emergencies presenting with acute visual loss pose significant diagnostic and therapeutic challenges, with potential for irreversible vision loss if not promptly recognized. A comprehensive approach that integrates clinical evaluation with advanced imaging modalities is essential for timely diagnosis, prognostic stratification, and management. Magnetic resonance imaging remains the gold standard for demyelinating optic neuritis, enabling differentiation among multiple sclerosis, neuromyelitis optica spectrum disorder, and myelin oligodendrocyte glycoprotein antibody-associated disease through lesion morphology and distribution, and is definitive for diagnosing pituitary apoplexy through the detection of sellar hemorrhage or infarction. Computed tomography is indispensable in the emergent triage of orbital trauma and in the rapid exclusion of intracranial hemorrhage in acute stroke. Optical coherence tomography (OCT) provides high-resolution quantification of neuroaxonal injury, with macular ganglion cell-inner plexiform layer thinning serving as a sensitive early marker of permanent damage compared to peripapillary retinal nerve fiber layer changes. OCT angiography further enhances vascular assessment in ischemic optic neuropathies and giant cell arteritis (GCA), offering a noninvasive alternative to fluorescein angiography. Ultrasonography contributes to the evaluation of GCA through the detection of the "halo sign" and provides bedside utility for measuring optic nerve sheath diameter in suspected intracranial hypertension. This narrative review highlights the complementary roles of these imaging techniques, underscoring their strategic application in optimizing outcomes for vision-threatening neuro-ophthalmologic emergencies.