A Case of Late-Onset Leber's Hereditary Optic Neuropathy in Association with Heteroplasmic m.11778G>A/ND4 Mutation.

A 68-year-old man described a progressive, painless, and bilateral reduction of visual acuity, with greater difficulties in central vision, over a period of 3 years. His past medical history was unremarkable, and he admitted a long exposure to tobacco smoking and moderate daily alcohol intake. The first ophthalmological evaluation confirmed a bilateral reduction of visual acuity, without other major findings. Visual fields showed a central scotoma in the right eye and a temporal pseudo-hemianopia in the left eye. The neurological examination was unremarkable. A slight cobalamin deficiency was detected after the first panel of investigations, and he was diagnosed and treated for the cause that seemed most obvious. Surprisingly, nutritional optic neuropathy was not his final diagnosis. This case shows how the paraclinical findings may help to address the correct diagnosis, summarizing a comprehensive approach to patients with progressive and bilateral visual loss and highlighting the main differential diagnosis.