From the Guidelines
Optic neuritis is best evaluated with MRI of the orbits and brain with contrast, which is the preferred imaging modality for diagnosis. The MRI typically shows enhancement and swelling of the optic nerve, with T2 hyperintensity representing inflammation. Contrast-enhanced fat-suppressed T1-weighted sequences are particularly useful for detecting the characteristic enhancement of the optic nerve, as reported in a study published in 2024 1. Brain MRI should also be performed to look for white matter lesions suggestive of multiple sclerosis, as optic neuritis is frequently associated with this condition.
Some key points to consider when evaluating optic neuritis with MRI include:
- T1-weighted postcontrast images with fat suppression can identify abnormal enhancement of the optic nerve in 95% of cases of optic neuritis 1
- MRI of the orbits alone is inadequate in the setting of acute vision loss, and should be performed along with an MRI of the head 1
- CT scans have limited value in diagnosing optic neuritis but may be used to rule out other orbital pathologies when MRI is unavailable
- Visual evoked potentials (VEPs) can complement imaging by demonstrating delayed conduction in the affected optic nerve
Imaging is especially important in atypical presentations, such as bilateral involvement, lack of pain, or severe vision loss, to exclude other conditions like compressive lesions or neuromyelitis optica. The radiological findings typically resolve within weeks to months as the inflammation subsides, though some patients may show persistent T2 hyperintensity or optic nerve atrophy on follow-up imaging, particularly in cases with poor visual recovery. According to the most recent and highest quality study available, MRI of the head and orbits with and without IV contrast is the most useful imaging modality for the evaluation of acute nontraumatic vision loss 1.
From the Research
Optic Neuritis Radiology
- Optic neuritis is often associated with multiple sclerosis, and magnetic resonance imaging (MRI) scans of the brain can show signal abnormalities that indicate a risk for the development of definite multiple sclerosis 2.
- MRI scanning of the brain is recommended in all cases of acute optic neuritis for diagnostic and prognostic purposes, and can show T2 ovoid high-signal white matter lesions located in perivenular regions perpendicular to ventricles with variable enhancement 3.
- The presence of three or more lesions on MRI scans is a strong indication of risk for the development of definite multiple sclerosis, with an adjusted rate ratio of 5.53 (95 percent confidence interval, 2.41 to 12.66) 2.
- Radiological findings in optic neuritis can include:
- Signal abnormalities on MRI scans of the brain
- T2 ovoid high-signal white matter lesions
- Lesions located in perivenular regions perpendicular to ventricles with variable enhancement
- The use of MRI scans in the diagnosis and management of optic neuritis is supported by multiple studies, including the Optic Neuritis Treatment Trial (ONTT) 3, 4.
- Current recommendations for the management of optic neuritis include the use of MRI scans as a compulsory investigation, with differential diagnostic cues and standard therapy patterns suggested based on the results 5.