The epidemiology of LHON varies geographically. In Western Europe, prevalence is estimated to be between 1 in 25,000 and 1 in 50,000. It is predominantly diagnosed in young adults (typically between 14 and 26 years of age) and affects males 4-5 times more often than females. Many carriers of the pathogenic mitochondrial mutations never develop vision loss.

LHON is caused by point mutations in mitochondrial DNA (mtDNA). These mutations affect the genes encoding for protein subunits of Complex I of the mitochondrial respiratory chain. This defect leads to a severe decrease in cellular energy (ATP) production and an excessive generation of reactive oxygen species (ROS), ultimately triggering apoptosis (cell death) of the highly energy-dependent retinal ganglion cells.

Approximately 90% of all LHON cases are caused by one of three primary mtDNA mutations:

• m.11778G>A (affecting the MT-ND4 gene) - The most common and typically the most severe.

• m.3460G>A (affecting the MT-ND1 gene).

• m.14484T>C (affecting the MT-ND6 gene) - Associated with the highest rate of spontaneous visual recovery.

Because mitochondria are inherited exclusively from the mother via the egg cell, a father with an LHON mutation cannot pass the disease to his children. A mother carrying the mutation will pass it to all of her offspring, though not all carriers will develop the disease.

Carrying an LHON mutation does not guarantee vision loss. Environmental triggers, notably heavy smoking and alcohol consumption, are known to significantly increase the risk of disease onset in carriers.

The classic clinical presentation of LHON is characterized by:

1. Subacute Vision Loss: Sudden, painless blurring of central vision beginning in one eye.

2. Sequential Involvement: The second eye usually becomes affected within weeks to a few months (typically within 8 weeks).

3. Visual Deficits: Dense central or centrocecal scotomas (blind spots in the center of the field of view) and dyschromatopsia (color vision impairment). This can lead to difficulty reading, recognizing faces, or performing other tasks requiring detailed central vision. 

While mostly limited to the eye, some patients develop "LHON Plus" syndromes, experiencing extraocular neurological symptoms such as tremors, movement disorders, peripheral neuropathy, or a multiple sclerosis-like illness particularly in women.

Diagnosis relies heavily on clinical suspicion, vision testing and genetic assessments.

• Clinical suspicion based on presentation: young patient (often male) with subacute, painless, bilateral central vision loss.

• Vision testing may include dilated fundus examination looking for optic disc swelling, visual field testing, color vision testing and optical coherence tomography (OCT) to observe thickening of the retinal nerve fiber layer, followed by progressive thinning as atrophy develops.

• Genetic testing and family history: confirmatory diagnosis via blood test for the three primary mtDNA mutations (m.11778G>A, m.14484T>C, m.3460G>A); expanded panels can detect rarer mutations if primary testing is negative;  maternal lineage history of vision loss can support a diagnosis.

Treatment combines disease-directed therapies with visual rehabilitation.

• Idebenone (Raxone): A synthetic coenzyme Q10 analog is currently the only approved disease-specific treatment for LHON. It acts as a mitochondrial electron carrier and antioxidant, bypassing the Complex I defect to restore ATP production. Clinical trials indicate it is most effective when started early in the disease course.

• Supportive Care: Avoidance of potential triggers such as smoking, binge alcohol consumption, and exposure to known or suspected mitochondrial toxins;  low-vision rehabilitation with optical aids;  and occupational, orientation and mobility training or support. 

• Gene Therapy: Recent clinical trials evaluating the intravitreal (injected into the eye) gene therapy lenadogene nolparvovec for the ND4 m.11778G>A mutation) have demonstrated sustained, bilateral visual improvement, marking a major milestone in restoring vision.

• Genetic counseling: Recommended for at-risk maternal carriers of the LOH mtDNA mutations.  

LOH prognosis is variable, depending heavily on the specific mutation, age of onset and individual factors. Recovery can occur spontaneously or with treatment, but is usually incomplete. The m.14484T>C (ND6) mutation has the best prognosis, with spontaneous partial visual recovery in roughly 37–58% of cases. The m.11778G>A (ND4) mutation, the most common, generally carries a poorer prognosis for spontaneous recovery. Most untreated patients are left with significant, often severe, bilateral visual impairment or legal blindness, though peripheral vision is typically preserved, allowing some functional independence. Emerging treatments (idebenone, gene therapy) are improving outcomes for a meaningful subset of patients, particularly when started earlier in the disease course.

1. Alorainy, J., Alorfi, Y., Karanjia, R., & Badeeb, N. (2024). “A Comprehensive Review of Leber Hereditary Optic Neuropathy and Its Association with Multiple Sclerosis-Like Phenotypes Known as Harding’s Disease.” Eye and Brain, Volume 16, 17-24. https://doi.org/10.2147/eb.s470184.

2. Hage, R. and Vignal-Clermont, C. (2021). “Leber Hereditary Optic Neuropathy: Review of Treatment and Management.” Front. Neurol. 12:651639. doi: 10.3389/fneur.2021.651639.

3. Klopstock, T., Zeng, Leopold H. and Priglinger, C.(2025). "Leber’s hereditary optic neuropathy – current status of idebenone and gene replacement therapies" Medizinische Genetik, 37: 57-63. https://doi.org/10.1515/medgen-2024-2066.

4. Shemesh A, Sood G, Blair K, et al. 2024. “Leber Hereditary Optic Neuropathy (LHON).” In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2026 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK482499/?utm_source=chatgpt.com.

5. Yu-Wai-Man P, Chinnery PF. (2021). “Leber Hereditary Optic Neuropathy.” In: Adam MP, Bick S, Mirzaa GM, et al., editors. GeneReviews® [Internet]. Seattle (WA): University of Washington, Seattle; 1993-2026. Available from: https://www.ncbi.nlm.nih.gov/books/NBK1174/?utm_source=chatgpt.com.