Introduction
Occurs due to a mutation in the mitochondrial DNA
- As mitochondrial DNA is always maternal, this is a maternal transmitted disease without full penetrance
- The loss of ATP production will cause an increased swelling of the optic disc and impaired axonal transport in the acute stage
- Affects 1 in 50,000
- Predominantly affects younger males
Dead Giveaways
The giveaways for this disease is not as sufficient, and will primarily depend on family history or genetic testing
Has a sudden onset, and is not slow approaching
Goldmann Perimeter
The optic nerve region has a more exaggerated blind spot. Additionally, there is a central/ceco-central scotoma
Acute LHON:
The biggest giveaway is fellow eye involvement.
Acute phase lasts only about 6 weeks, however, 6 weeks later, the fellow eye will be involved
Chronic LHON:
The biggest giveaway was the drastic thinning of the RNFL, and the shallowing of the foveal pit
The shallowness of the fovea. May impact vision, with VA being as poor as 6/60, or worse, finger counting
diagnostic features
Acute LHON
As RNFL swells in the acute phase, the optic nerve head becomes increasingly red and hyperaemic, with occasional tortuous vessels. However, 20-40% of the time, it is normal
VA is reduced
Very red and hyperaemic, borders are slightly less defined
Chronic LHON
The RNFL will thin and undergo atrophy in the chronic phase, making the disc more pale, and the border becomes more distinct and clearly defined.
The normal feathery appearance of the disc is not present due to RNFL death.
The GC also shows diffuse thinning --> papillomacular
Severe dyschromatopsia, usually tritan errors.
