BACKGROUND: Optic neuritis is an acute inflammation of the optic nerve that results in painful loss of vision. Patients often present to a general practitioner, and early recognition is important as treatment may improve the speed of vision recovery. OBJECTIVE: This article provides information on the signs and symptoms of optic neuritis and discusses appropriate referral, investigations and management. DISCUSSION: Optic neuritis is the presenting symptom in up to one-fifth of people with multiple sclerosis. Diagnosis of optic neuritis is based on history and examination, therefore obtaining pertinent information and performing proper ophthalmic examination is essential. Prompt recognition and appropriate referral is important to facilitate investigations such as magnetic resonance imaging of the brain that can help predict risk in the development of multiple sclerosis.