Leber Hereditary Optic Neuropathy (LHON)

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Aetiology

  • Hereditary, mitochondrial inheritance (only inheritable from the mother)
    • Approximately 20% of male carriers and 5-10% of female carriers become symptomatic
    • About 90% of cases triggered by one of three mutations (11778, 3460, 14484)

Clinical Presentation

  • Mostly young adult men, but manifestation can occur at any age and also in women
  • Acute unilateral or bilateral painless visual loss
    • Simultaneous bilateral involvement in 50%
    • Sequential involvement in 50%, with intervals ranging from days to weeks/months (up to years)
    • Progressive visual impairment, typically reaching from 0.1 to counting fingers over time
    • Central or centrocecal scotoma
  • Findings:
    • Initially, the optic disc is often normal
    • Possibly mild disc swelling with hyperemia
      • No leakage in fluorescein angiography
    • Subsequently, disc pallor

Work-up

  • Genetic screening for the three most common mutations
    • If negative and symptoms are typical, analyse the entire mitochondrial genome
  • Imaging: Rule out optic neuritis/NMO, usually unremarkable
  • OCT: Retinal nerve fiber layer (RNFL) + Ganglion cell layer
  • Visual field examination
  • Consider cardiac evaluation due to an increased risk of arrhythmias

Treatment

  • No smoking and alcohol
  • No excessive sports, such as marathons
  • Trial with Idebenone (Raxone): potential improvement/stabilization of visual function; effective if started within 1 year of initial manifestation
  • Genetic counseling
  • Future availability of gene therapy possible, currently in clinical trials

Differential Diagnoses

Sources