Leber Hereditary Optic Neuropathy with Interval of Visual Loss Greater Than 12 Months.

A 28-year-old man presented with severe left visual loss and normal right visual acuity. The left fundus examination showed temporal pallor and complete absence of the nerve fibre layer (NFL) of papillomacular bundle. Right fundus examination showed focal loss of inferotemporal NFL. Magnetic resonance and serum aquaporin-4 antibody were negative. After 14 months of the initial visual involvement, the patient suffered subacute visual loss in contralateral eye. Genetic study revealed the 11778 point mitochondrial DNA (mtDNA) mutation associated with Leber hereditary optic neuropathy (LHON). Although very rare, interval of involvement of second eye greater than 12 months can occurs in LHON. Detailed optic nerve examination and careful interpretation of optical coherence tomography (OCT) printout support the diagnosis.