Editor,—Leber's hereditary optic neuropathy (LHON) is a maternally inherited mitochondrial disease that results in bilateral visual loss. It primarily affects young men. The typical optic nerve head appearance is one of circumpapillary telangiectatic microangiopathy, swelling of the nerve fibre layer around the optic disc, and the absence of capillary leakage on fluorescein angiography.1

The mitochondrial inheritance of the disease was confirmed in 1988 by Wallace et al who identified a mitochondrial DNA replacement mutation at nucleotide position 11778.2Further mutations have been identified at positions 3460, 14484, and 15257.3 4 The 11778 mutation is responsible for 31–89% of LHON pedigrees in Europe, North America, and Australia, while the 3460 and 14484 mutations each account for approximately 10–15% of cases.5 The discovery of the molecular basis of LHON has provided insights into the heterogeneous clinical spectrum of disease that may result. Although the causal mutations are established, the pathophysiology of the optic nerve damage is not known. The relation between metabolic dysfunction, such as diabetes …