A 25-year-old man presents with acute, painless loss of vision in the right eye. The appearance of the optic nerve of the right eye is hyperemic. Of the entities listed, the most likely cause may include:

Leber hereditary optic neuropathy (LHON) Hereditary, toxic, and nutritional deficiency optic neuropathies commonly present with bilateral, insidious vision loss. In some cases, there can be asymmetry in visual acuity and visual fields. LHON often presents as acute or subacute unilateral vision loss that is followed within several months by vision loss in the fellow eye. The appearance of the optic nerve in LHON is characterized by a triad of circumpapillary telangiectasia, swelling of the nerve fiber layer around the disc, and absence of leakage on fluorescein angiography. LHON should be included in the diagnosis of acute unilateral vision loss from such disorders as optic neuritis and ischemic optic neuropathy.