• Optic neuritis and eye movement disorders, particularly internuclear ophthalmoplegia, are a common cause of disability in patients with multiple sclerosis. • Optic neuritis causes acute, unilateral, painful visual loss which progresses over days to weeks and spontaneously recovers over weeks to months. Initially, the optic nerve head looks normal in two-thirds of cases. • Persistent subjective complaints of abnormal vision are common after optic neuritis and are often explained by defects in contrasts sensitivity. • Optic atrophy may occur after a single episode of optic neuritis, supporting the argument for early therapeutic intervention. • Short tau inversion recovery (STIR) MRI sequences are best at showing optic nerve abnormalities. • Optic neuritis does not require acute intervention, but may appropriately be treated with high dose steroids. • There is no role for standard dose (1 mg/kg/day) oral prednisone in the treatment of optic neuritis. • Brain MRI lesions identified at the time of an initial episode of optic neuritis are highly predictive of future MS risk. • Initiation of immunodulatory therapy in the setting of optic neuritis and at least two MRI brain lesions should be considered. • Proton density MRI is the most sensitive method for detecting a medial longitudinal fasciculus lesion in the setting of internuclear ophthalmoplegia.