What is LHON?
Leber's Hereditary Optic Neuropathy (LHON) is a genetic eye disease which leads to sudden loss of central vision. LHON is caused by mutations in the genetic code of the mitochondria which are small bodies within the cell. The mitochondria convert energy locked in our food into energy for the cells to use. If the mitochondria can no longer fulfill this function, the lack of energy can lead to degeneration and death of retinal ganglion cells (RGCs). RCGs are the nerve cells which relay visual information from the eyes to the brain. A loss of these cells subsequently leads to a degeneration of the optic nerve and vision loss.
While the condition usually emerges in a person's teens or twenties, rare cases may appear in early childhood or later adulthood. For unknown reasons males are more affected than females.
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Normal vision vs. Leber Hereditary Optic Neuropathy
What is known though is that LHON follows a mitochondrial pattern of inheritance, which is also known as maternal inheritance. Only egg cells and not sperm cells contribute mitochondria to a developing embryo, therefore only females can pass mitochondrial conditions to their children. Males affected by Leber's or carrying LHON mutations do not pass the condition to their children.
Often, people who develop LHON have no family history of the condition. Since a person can carry a mitochondrial DNA mutation without experiencing any symptoms, it is currently impossible to predict which members of a family who carry a mutation will eventually develop vision loss. LHON is a very rare condition with the prevalence of it still unknown in most populations, but it is thought to affect between one in 30,000 to one in 50,000 individuals worldwide. Research has revealed that three particular mutations in mitochondrial genes account for between 85% – 90% of cases of LHON.
What are the symptoms of Leber's Hereditary Optic Neuropathy
Symptoms of LHON include:
- a sudden painless blurring and clouding of vision, in one or simultaneously in both eyes.
- over time decreased loss of sharpness (visual acuity) and color vision
- decreased central vision with peripheral vision staying generally intact
What to expect from Leber's Hereditary Optic Neuropathy
There is no cure for Leber's. However, research is continually being carried out to determine treatment options. It is important to have your eyes monitored regularly for any changes or complications.
More information about Leber's Hereditary Optic Neuropathy
There is extensive information available about LHON. The information included is intended to inform you about the basics of this eye condition, and is not intended as a replacement for information from your physician or eye specialist. Information regarding assistive devices that can help you if you have been diagnosed with LHON is included. Our recommendations can be found under Tools and Resources.