Frequently asked questions

LHON is a rare genetic eye condition that runs in families and severely impacts visual acuity.Footnote¹ Symptoms in LHON begin with sudden loss of sight and painless blurring and clouding of central vision in one or both eyes.Footnote² It results from cell dysfunction, and eventually cell death in the optic nerve that relays visual signals from the eye to the brain.Footnote³

LHON begins with the following symptoms

a Sudden vision issues in one or both eyes
b Painless blurring in the centre of the eye
c Blurring of vision
d Loss of sharpness
e Loss of colour vision

If you think you might have LHON, do not wait for symptoms to get worse. Look for an LHON specialist such as an ophthalmologist. If you cannot approach an ophthalmologist directly, talk to your GP about your suspicions around LHON to speed up the diagnosis. They can refer you to an eye care specialist for further management of your condition.

LHON is a rare genetic condition that leads to symptoms such as sudden sight loss and blurred vision. These are caused by mutations in the mitochondrial DNA. A mother with an LHON mutation passes it on to all her children. However, a father who has LHON cannot pass it on to any of his children. This is because the mitochondria for the developing baby come from the mother’s egg cells and not the father’s sperm cells. A second form of LHON mutation in a nuclear encoded gene, DNAJC30, has also been established—described as an autosomal recessive mode of inheritance for LHON (arLHON).Footnote⁶

LHON is a progressive disease leading to severe vision impairment. Most patients with LHON become legally blind. Some people with LHON have experienced partial recovery of sight in one or both eyes. Speak to an ophthalmologist if you have symptoms or a family history of LHON. They can guide you on the possible options, such as treatment, follow up and low vision rehabilitation.

People without a family history of LHON are known to develop the condition.Footnote⁴ Around one in three cases appears to be sporadic with no definitive family history.⁷ In addition, a second form of LHON mutation in a nuclear encoded gene, DNAJC30, has also been established—described as an autosomal recessive mode of inheritance for LHON (arLHON).Footnote⁶
If the ophthalmologic assessments and molecular genetic testing leave any uncertainty about the diagnosis of LHON, further investigations are appropriate to exclude other potentially reversible causes of bilateral optic neuropathy and to allow for the initiation of prompt treatment before visual loss becomes irreversible.Footnote⁴

Molecular genetic testing approaches can include a combination of gene-targeted testing methods such as, targeted mtDNA analysis for pathogenic variants, multigene panel, and complete mtDNA sequencing. Clinical diagnosis for nuclear mutations such as, arLHON can be performed through patient-derived fibroblast cell lines obtained by skin biopsy.Footnote⁶

The threat of acquiring LHON never goes away but you can avoid certain lifestyle factors to reduce the risk. Those with an LHON mutation are advised to stop smoking, moderate their alcohol intake and avoid certain drugs. Men are four to five times more likely to be affected by LHON than women. The first signs of vision loss usually appear between the ages of 15 and 35 years. In rare cases, symptoms can occur between 2 and 87 years of age. LHON affects women more commonly during the menopause years.

A mother with an LHON mutation passes it on to all her children. However, a father who has LHON cannot pass it on to any of his children. This is because the mitochondria for the developing baby come from the mother’s egg cells and not the father’s sperm cells. So, any mutations in the mitochondria can only be inherited maternally.
However, around one in three cases also appears to be sporadic with no definitive family history.⁷ In addition, a second form of LHON mutation in a nuclear encoded gene, DNAJC30, has also been established—described as an autosomal recessive mode of inheritance for LHON (arLHON).Footnote⁶

For patients and their families, LHON can come as a shock. However, most of the affected people adjust to their new level of visual functioning within a few years after the first symptoms of LHON appear.Footnote⁸ There are a number of patient advocacy groups and online support groups for patients with LHON.

Sometimes patients experience nadir even during treatment, but this shouldn’t stop you from continuing your medication. In some cases, after an initial deterioration of visual acuity and reaching nadir, patients have achieved a clinically relevant recovery after treatment maintenance.