[Diplopia: An important symptom in internal medicine!]

Diplopia is defined as "double vision" when looking at a single object. Monocular diplopia is related to an ocular disorder and must be differentiated from binocular diplopia which is secondary to ocular misalignment. The examination of the patient with binocular diplopia is often challenging for non-specialists. However, a careful and systematic clinical examination followed by targeted ancillary testing allows the clinician to localize the lesion along the oculomotor pathways. The lesion may involve the brainstem, the ocular motor nerves III, IV or VI, the neuromuscular junction, the extraocular ocular muscles, or the orbit. Causes of binocular diplopia are numerous and often include disorders typically managed by internal medicine such as inflammatory, infectious, neoplastic, endocrine, and metabolic disorders. In addition to treating the underlying disease, it is important not to leave diplopia uncorrected. Temporary occlusion of one eye by applying tape on one lens or patching one eye relieves the diplopia until more specific treatments are offered should the diplopia not fully resolve.