To assess the rate of optic neuritis misdiagnosis applying the 2022 optic neuritis diagnostic criteria to patients with noninflammatory optic neuropathy and optic nerve (ON) T2-hyperintensity in at least one eye.

Recent updated diagnostic criteria for optic neuritis include ON-T2-hyperintensity, with or without associated contrast enhancement, as a paraclinical test. However, isolated ON-T2-hyperintensity is a nonspecific finding that can be found in any optic neuropathy/severe retinopathy.

Retrospective study of consecutive patients who underwent brain/orbit MRI with/without contrast between 07/01/2019-06/30/2022. Patients with ON-T2-hyperintensity in at least one eye were included. Medical record review provided the ON-T2-hyperintensity underlying etiology. The 2022 optic neuritis diagnostic criteria were applied to noninflammatory optic neuropathies.

Of 150 patients included (mean age 56±19 years; 55 % men), 85/150 had compressive optic neuropathy (0/85 fulfilled the criteria); 32/150 had glaucomatous optic neuropathy (0/32 fulfilled the criteria); 13/150 had ischemic optic neuropathy (4/13 fulfilled the criteria as definite optic neuritis due to contrast enhancement of the ON head); 12/150 had papilledema-related optic neuropathy (0/12 fulfilled the criteria); 8/150 had hereditary (3), radiation-induced (3), nutritional (1), traumatic (1) optic neuropathies (0/8 fulfilled the criteria).

The application of the 2022 optic neuritis diagnostic criteria in 150 consecutive patients with noninflammatory optic neuropathy and ON-T2-hyperintensity in at least one ON resulted in misdiagnosis of optic neuritis in only 4 patients because of ON head enhancement, all with nonarteritic anterior ischemic optic neuropathy. Neuro-ophthalmologic evaluation and exclusion of the ON head as a location in the MRI criteria would have prevented optic neuritis misdiagnosis in our study. The use of these criteria by neurologists or neuroradiologists without neuro-ophthalmologic evaluation can rarely lead to optic neuritis diagnosis in excess, of particular importance given the proposed inclusion of the ON as the fifth location for dissemination in space in the multiple sclerosis criteria.