Optic Neuropathy Essay

Leber hereditary optic neuropathy (LHON) is an inherited form of vision loss. The prevalence of LHON in most populations is unknown and the relative frequency of the different LHON-causing mtDNA variants is said to vary throughout the world. Overall, the m.11778G>A variant is the most prevalent, accounting for 70% of cases among northern European (Mackey et al 1996) and approximately 90% of cases in Asian populations (Mashima et al 1998, Jia et al 2006). It affects 1 in 8,500 to 1 in 50,000 people in northeast England and Finland respectively (Man et al 2003, Spruijt et al 2006, Puomila et al 2007). LHON is characterized by bilateral, painless subacute visual failure that develops during young adult life. Males are four to five times more likely than females to be affected (Yu-Wai-Man et al 2009). In the acute phase the affected individuals are usually entirely asymptomatic until they develop visual blurring affecting the central visual field in one eye; similar symptoms appear in the other eye at an average of two to three months later. In about 25% of cases, visual loss is bilateral at onset. The ocular fundus may …show more content…
These genes are found in the mtDNA and provide instructions for making a protein involved in normal mitochondrial function, mutations in any of these genes disrupt this process and lead to impaired glutamate transport and increased mitochondrial reactive oxygen species production that trigger retinal ganglion cell death via an apoptotic mechanism (Danielson et al 2002, Beretta et al 2004, Zanna et al 2005). However, the selective vulnerability of retinal ganglion cells in LHON remains unexplained. A significant percentage of people with a mutation that causes LHON do not develop any features of the disorder. Specifically, more than 50 percent of males with a mutation and more than 85 percent of females with a mutation never experience vision loss or related health