ABSTRACT
Leber's hereditary optic neuropathy is a rare genetic disorder affecting the retinal ganglion cells leading to a persistent severe bilateral loss of visual acuity within weeks or months. Males are much more likely to be affected than females, disease onset in most cases takes place between age 15 and 35 years. The disease is caused by point mutations in the mitochondrial DNA. The penetrance of the disease is incomplete, i.e., not all mutation carriers develop clinical symptoms. The phenotype is relatively uniform, but age at onset, severity and prognosis may vary even within the same family. Environmental and endocrine factors, optic disc anatomy as well as mitochondrial and nuclear genetic factors are discussed to influence penetrance as well as interindividual and intrafamilial variability. However, only cigarette smoking and excessive alcohol consumption have been shown to trigger disease onset. The disease is characterised by a central visual field defect, impaired colour vision and fundoscopically a peripapillary microangiopathy in the acute phase. Most patients end up after some months with a severe visual loss below 0.1 and in most cases there is no significant improvement of visual acuity in the course. In rare cases patients experience a mostly partial visual recovery which depends on the type of mutation. For confirmation of the diagnosis a detailed ophthalmological examination with fundoscopy, family history and genetic analysis of the mitochondrial DNA is needed. To date, there is no proven causal therapy, but at early disease stages treatment with idebenone can be tried.
