[Sudden onset diplopia].

Sudden onset diplopia may occur secondary to something as simple as uncorrected refractive error or as complicated as brainstem disorders in conjunction with other symptoms. Therefore, all complaints of diplopia must be a cause for concern. Ophthalmologists have to determine if diplopia is the first sign of a systemic or neurological disorder, which needs to be referred to a specialist or can be managed by the practitioner. In this paper the importance of the case history, primary diagnostic options, the indications for supplementary testing with computed tomography (CT) or magnetic resonance imaging (MRI) as well as treatment options when a patient complains of sudden onset diplopia are discussed.