What is LHON?
Leber hereditary optic neuropathy is a rare hereditary condition, which is caused by mutations in the mitochondrial genome. Those mutations can lead to the death of cells in the optic nerve, which would impair the vision of the individual.
It is passed down by the mother, since only the female egg cells contribute mitochondria to the offspring and a father cannot pass it down, even if they themselves have the condition or just the genes causing it.
Who is at risk of having LHON?
Since the condition is hereditary and can be inherited only by the mother, people who are at risk include everyone who has or had a female family member, who has been diagnosed with the condition. Even if you carry the genes causing the condition, chances are that you will not develop it.
Sex of the individual is one of the factors that determines whether you would develop the condition. The reason for that is not clear, but Leber hereditary optic neuropathy is much more likely to occur in males. There are speculations that smoking and alcohol could be the reason for the higher ratio, as males are more likely than females to do either.
Age is another factor, with LHON appearing mostly in young adults. While the age of onset is mostly between 20 and 30 years, it can also appear in any age group.
What are the symptoms of LHON?
LHON is painless and the main way to tell it's there is either by changes in the vision or by establishing it through a medical exam, if you are aware you might be at risk of it. Changes in the vision that can be the result of LHON can include:
- sudden blurring or clouding of vision
- reduced colour perception
- loss of central vision
Symptoms can appear in either one or both eyes. In almost all cases, even if only one eye was affected initially, within a few months the other one would contract LHON as well.
This condition affects mostly the central vision, while the peripheral one remains mostly intact. In some cases vision can slightly improve over time after the initial loss of sight, but that mainly depends on type of mutation.
In the most common type of mutation, vision loss is severe and the recovery is minimal. There is however a mutation, where the loss is not that big and the individuals can recover most of it. In the third common case, the loss of vision is moderate, but keeps worsening over time. Those 3 mutations amount to about 9/10 of the LHON cases.
Is there a treatment or a cure for LHON?
Right now there is no cure for LHON. While there are a few methods that can give fair results, there is no defined treatment for this condition. Some mitochondrial supplements and Idebenone may prove beneficial. Other methods such as gene therapy are being actively researched.
Visual aids can help you perform tasks as usual. There are also services available to adjust you to or aid you with this new lifestyle.
Developing a LHON can be deeply stressful, but you will still be able to lead a fulfilling life.