Leber’s hereditary optic neuropathy

Leber’s hereditary optic neuropathy, known for short as LHON, is a rare inherited mitochondrial disorder. It causes sudden, painless loss of central vision, often in young, otherwise healthy adults. It occurs when genetic changes (mutations) in the mitochondrial DNA impair the cells’ ability to produce energy, leading to damage of the optic nerve and retina.

For those affected, loss of vision often occurs suddenly and without warning. While the condition affects fewer than 1 in 30,000 people in the UK, its impact is profound, altering daily life, independence and future plans for those diagnosed.

You’ll find more information below on LHON disease, including symptoms, causes and support available for anyone in the UK affected by this form of mitochondrial disease.

What is Leber’s hereditary optic neuropathy?

LHON is one of the most common types of mitochondrial disease and is caused by mutations in mitochondrial DNA. Predominantly impacting young adult males, it generally affects the optic nerve – that’s the large nerve that leaves the back of each eye to carry visual information to the brain – where the vision centres are located.

What does LHON stand for?

LHON stands for Leber’s hereditary optic neuropathy. It’s a form of inherited optic neuropathy, meaning it's a disease of the optic nerve. It’s often referred to as LHON for short.

What are the symptoms of LHON?

Initial symptoms are blurring of the central vision and loss of colour vision. Most patients with LHON disease usually first notice problems between the ages of 15 and 35, but people of any age can be affected. Often, the symptoms start in just one eye, but generally the other eye is affected within weeks or months. In around a quarter of cases, the onset of vision loss occurs in both eyes at the same time.

Although usually not painful, LHON leads to severe vision loss and eventual blindness with a significant impact on quality of life.

What causes Leber’s hereditary optic neuropathy?

Most LHON patients carry one of three specific mutations in their mitochondrial DNA. Usually this is inherited from the mother, but sometimes the error arises for the first time in the patient. Although both sexes can have the error, more men go on to develop loss of vision.

The most frequently affected genes in Leber’s are MT-ND1 (m.3360G>A), MT-ND4 (m.11778T>C), and MT-ND6 (m.14484T>C). These genes carry the instructions for producing proteins essential for the cell’s energy generation.

Why does Leber’s hereditary optic neuropathy affect more males?

Around 8 out of 10 people diagnosed with Leber’s are male, but we don’t yet know why this form of mitochondrial disease affects men much more often than women. The risk of losing vision is much less if someone is older than the age of 50. If someone carrying a LHON mutation smokes or binge drinks, they have a much higher risk of becoming affected.

Are there any treatments for LHON?

LHON is the only form of mitochondrial disease for which there is an effective therapy available in the UK. In August 2025, the National Institute for Health and Care Excellence (NICE) approved the use of a drug called idebenone on the NHS for the treatment of Leber’s hereditary optic neuropathy in people aged 12 and over.

The drug had already been available in Scotland and Wales for a number of years but hadn’t been licenced for use in England before. The decision brought an end to that geographic inequality and means that LHON patients in England finally have access to a drug that could potentially improve their quality of life and help improve their eyesight.

Idebenone, also known by its brand name Raxone and made by Chiesi, is a pill that works by supporting mitochondrial function in the optic nerve and retina. The drug is thought to help improve energy production in the cells of the retina and optic nerve, potentially preventing further loss of vision, and in some cases promoting recovery of vision.

While clinical studies have shown that idebenone can help stabilise vision in some patients, it must be stressed that not every patient who is treated will benefit, and results will vary.

In line with NICE’s recommendations, LHON patients in England who are 12 years and over should speak to the healthcare professional responsible for their care to understand whether idebenone is the right treatment for them. According to NICE’s standard timelines, the drug is likely to be available to eligible patients in early 2026. A LHON consensus guidelines is currently being developed by a group of experts, under the leadership of the University of Cambridge’s Professor Patrick Yu-Wai-Man, about who should be treated with idebenone, for how long and what monitoring will be needed to assess various aspects of vision.

Among those patients who respond to the treatment, idebenone will not lead to complete recovery of vision. Other treatments are being investigated, in particular gene therapy for the MT-ND4 (m.11778T>C) mutation, which is the most common cause of LHON in the UK and worldwide, accounting for over 60% of cases.

Support for Leber’s hereditary optic neuropathy

Specialist neuro-ophthalmology and mitochondrial clinics across the UK are there to provide expert care for LHON patients, including diagnosis, ongoing monitoring and management of symptoms. Genetic counselling is also available through NHS services to help families understand inheritance patterns and support future family planning.

The LHON Society is a UK-based, patient-led charity and support group for individuals and families affected by Leber’s hereditary optic neuropathy. The society provides information, peer support and advocates for the LHON community, working to raise awareness, fund research into treatments and represent members’ interests to healthcare providers and scientific communities.

The Lily Foundation provides practical and emotional support for families living with LHON. We also advocate for patients and fund critical research aimed at developing new treatments. Indeed, we played an important role in the licensing of idebenone as a treatment for LHON and were proud to be a key stakeholder throughout the NICE submission.

Whether you’ve just received a diagnosis of Leber’s or have been living with this mitochondrial syndrome for a while, our Mitochondrial Disease Q&A page can help answer any other questions you might have.