Leber's hereditary optic neuropathy: the clinical relevance of different mitochondrial DNA mutations.

Leber's hereditary optic neuropathy (LHON) was first described in 1858 by von Graefe.' It was later named after Theodore Leber in recognition of his paper published in von Graefe' Archives of Ophthalmology in 1871.2 Characteristically the disease presents in the second or third decades oflife as a subacute optic neuropathy, developing sequentially in the two eyes, with vision reduced to worse than 6/60, large central visual field defects, poor colour vision, and little recovery ofvision. The importance of LHON lies in its ability to cause such severe and usually permanent visual loss in generally fit young people who are about to start or have recently begun employment or higher education, and the ramifications of diagnosing an inherited disease to other members of the patient's family. The recent discovery of various mutations of mitochondrial DNA in families with LHON has provided both an important diagnostic tool and also a means to improve our ability to determine prognosis and to understand the pathogenesis of the disease.