Optic neuropathy (ON) is defined as the reduction of vision due to inflammatory lesion of the optic nerve. The patient with ON has to be evaluated clinically but also with complex techniques (magnetic resonance imaging, visual evoked potentials, cerebrospinal fluid examination) because ON could be the presenting symptom in multiple sclerosis patients. Corticosteroids should be administrated intravenous and the patient should be followed by the neurologist in order to signal the appearance of new neurological signs.