Leber's hereditary optic neuropathy (LHON) is caused by point mutations in mitochondrial DNA. The authors report a case of a middle-aged man with genetically confirmed LHON, combined with bilateral normal tension glaucoma (NTG).

A 48-year-old man presented with complaints of decreased visual acuity in his left eye. His corrected visual acuity was 20/16 in the right eye and 20/63 in the left eye. The fundus photographs revealed a bilateral, superotemporal and inferotemporal retinal nerve fiber layer defect, corresponding to his visual field defect. The patient was diagnosed with bilateral NTG. After 2 months, the patient's corrected visual acuity in the left eye worsened to counting fingers and a central visual field defect was noticed in the Humphrey visual field test in the left eye. At 4 months after the initial visit, his corrected visual acuity in the right eye became 20/100, and the Goldmann visual field test demonstrated cecocentral scotoma. The fundus photographs showed a papillomacular bundle defect in his left eye. At 7 months after the initial visit, his visual acuity was hand movement in the right eye and a finger count in the left eye. A series of LHON gene mutation tests revealed a 11778 mitochondrial gene mutation, and the patient was diagnosed with LHON.

Proper diagnosis of LHON might be disturbed by atypical manifestation of other optic nerve diseases, such as glaucoma. Therefore, suspecting LHON and checking for gene mutations as part of the work-up in patients with bilateral optic neuropathy is critical.