Leber Hereditary Optic Neuropathy (LHON) is a rare inherited condition that causes vision loss by damaging the retinal ganglion cells and optic nerve, the pathway that carries visual information from the eye to the brain.

Unlike inherited retinal diseases (IRDs), which primarily affect the retina’s light-sensing cells, LHON is an inherited optic neuropathy. It affects cells that transmit visual information from the retina to the brain and typically causes sudden, painless loss of central vision, often beginning in one eye and affecting the other eye within weeks or months.

LHON most commonly affects young adult males, although people of any sex can carry the genetic changes that cause the condition and may experience vision loss.

Advances in mitochondrial genetics, diagnosis, and gene-based therapies have increased understanding of LHON and created new opportunities for treatment and research.

Retina International works with people affected by LHON, patient organisations, researchers, clinicians, and partners worldwide to improve awareness, support patient involvement, and advance research into inherited vision conditions.

Leber Hereditary Optic Neuropathy is an inherited optic neuropathy that causes degeneration of the retinal ganglion cells and optic nerve.

The optic nerve contains millions of nerve fibres that transmit visual signals from the eye to the brain. When these cells become damaged, the brain cannot receive complete visual information, resulting in vision loss.

LHON primarily affects the retinal ganglion cells, particularly those involved in central vision. Because of this, LHON is not considered an inherited retinal dystrophy (IRD), even though the affected cells are located within the retina.

The condition typically presents with:

· Sudden loss of central vision

· Reduced ability to see fine details

· Difficulty reading and recognising faces

· A central or central-to-peripheral blind spot

Peripheral vision is often preserved, although some people may experience broader visual changes.

LHON is a mitochondrial disease, meaning it is caused by changes in mitochondrial DNA (mtDNA), which affects how cells produce energy.

The condition is sometimes referred to as:

· Leber optic neuropathy

· Leber hereditary optic atrophy

Unlike many inherited retinal diseases, LHON often begins suddenly, meaning people may need to adapt quickly to significant changes in vision.

The impact may affect:

• Education
• Employment
• Mobility
• Independence
• Emotional wellbeing

Support may include:

• Low vision rehabilitation
• Assistive technology
• Workplace and educational accommodations
• Peer support
• Patient organisations

Early access to practical and emotional support can help people adapt and maintain independence.

The experiences of people living with LHON are important in shaping research, healthcare services, and advocacy priorities.