Diagnosis and classification of autoimmune optic neuropathy.

The spectrum of autoimmune optic neuropathies (ON) is extending. The phenotypic spectrum includes single isolated optic neuritis (SION), relapsing isolated optic neuritis (RION), chronic relapsing inflammatory optic neuropathy (CRION), the neuromyelitis optica (NMO) spectrum disorder, multiple sclerosis associated optic neuritis (MSON) and unclassified optic neuritis (UCON) forms. Epidemiological data suggests a slight female predominance. The ethnic heritage is relevant as Caucasian patients are more likely to suffer from MSON, whilst SION, RION, CRION and NMO are more frequent in non-Caucasian patients. Importantly, prognosis for recovery of visual function is good in MSON, but poorer in NMO and CRION which also have a high chance for recurrent episodes. Testing for serum anti-AQP4 autoantibodies is advised in all patients with severe, atypical or recurrent ON because of the high diagnostic specificity. The diagnostic specificity may be aided by testing for glial biomarkers in the CSF and prognostic accuracy by testing for biomarkers for neuroaxonal degeneration. Optical coherence tomography is a highly accurate tool to document the final outcome. The current clinical classification criteria rely on the phenotype, response to treatment and presence of anti-AQP4 autoantibodies.