[Leber hereditary optic neuropathy: differential diagnosis].

The diagnosis of Leber hereditary optic neuropathy is suspected in the siblings of an affected person that complains of a decrease in visual acuity. It can also be suspected in a young subject, especially a male, with no medical history that presents with an optic neuropathy. Leber hereditary optic neuropathy is a diagnosis of exclusion. The search for differential diagnoses is essential in all cases, even when a mutation of the mitochondrial DNA was found in the patient of in a healthy carrier maternal relative. This is the interest of multimodal imaging and electrophysiology that allow to exclude retinal pathology mimicking optic neuropathy. A neuroradiological assessment must be systematically prescribed to eliminate a compressive lesion and/or intracranial hypertension. This assessment also provides information on a possible hypersignal of the optic nerve, the appearance of which can be an argument for orientation towards different causes of optic neuritis. Finally, a deficiency or toxic cause must be ruled out.