Most cases of optic neuritis are retrobulbar and involve no changes in the fundus, or optic disk, during the acute episode. With time, variable optic disk pallor may develop. Typical retrobulbar optic neuritis presents with sudden or rapidly progressing monocular vision loss in patients younger than 50 years. There is a central visual field defect that may extend to the blind spot. Pain on movement of the globe is common. The pupillary light response is diminished in the affected eye. Over time the vision improves partially or completely; minimal or severe optic atrophy may develop. Papillitis, inflammation of the intraocular portion of the optic nerve, will accompany disk swelling, with a few flame hemorrhages and possible cells in the vitreous.
Optic neuritis must be differentiated from papilledema (bilateral disk swelling, typically with no acute visual loss with the exception of transient visual changes), ischemic neuropathy (pale, swollen disk in an older individual with sudden monocular vision loss), tumors, and metabolic or endocrine disorders. Most cases of optic neuritis are of unknown etiology. Some known causes of optic neuritis include demyelinating disease, infections (including viral, syphilis, tuberculosis, sarcoidosis), or inflammations from contiguous structures (sinuses, meninges, orbit).
Treatment is controversial; often none is recommended. Oral steroids may worsen prognosis in certain cases. Intravenous steroids should be considered after consultation with an ophthalmologist.