Visual loss in the young adult can be caused by demyelinating diseases, inflammatory and autoimmune processes, infections, ischaemic events, and compressive lesions of the optic nerve. Diagnosis of the aetiologies of visual loss is reached by combining data from radiological studies, electrophysiological tests, and blood and cerebrospinal fluid analysis. Treatment is primarily aimed at decreasing the insult on the optic nerve and eventually controlling the primary disorder. The literature discusses separately the different aetiologies of visual loss. We present a review of the clinical characteristics of visual loss in the young adult, the different diagnostic measures, and the latest therapeutic strategies. The aim of this work is to summarise this entity in a practical way to guide clinicians in the diagnosis and management of this disorder.