The term is applied to inflammation, demyelinization or degeneration of the optic nerve with impairment of its function.
When optic neuritis restricts to retrobulbar portion of the nerve without any changes in the fundus, it is termed retrobulbar neuritis.
When the changes are detectable at the fundus ophthalmoscopically. it is termed papillitis (intra ocular optic neuritis).
When involvement is of both of retina and papilla, it is termed optic neuroretinitis.
The etiologic factors include bacterial meningitis, encephalomyelitis, following an exanthem, demyelinating diseases, drugs/toxins (chloramphenicol, vincristine, ethambutol, phenothiazines,
Treatment is with high doses of systemic steroids. Most cases begin to respond in 1 to 4 weeks, the vision reverting to normal in weeks or months. Permanent impairment of vision may occur in some instances.