Leber’s Hereditary Optic Neuropathy (LHON)

Leber’s Hereditary Optic Neuropathy (LHON) symptoms usually begin as sudden, painless loss of central vision. The classic pattern is for one eye to suddenly lose central vision, then on average 8 weeks later the other eye also loses central vision, though many variations on this pattern are possible. After this “acute phase,” severe visual loss in both eye remains. Reading, driving and recognizing faces are impossible. Peripheral vision generally remains intact so the affected individual can walk around independently. Since the LHON affected often does not “look blind,” those around them struggle to understand their situation and don’t realize how profound is their vision loss.

LHON is a genetic disorder that can cause the optic nerve to atrophy but does not always do so. It is the most common mitochondrial disease. About 45 mutations have been linked to LHON. The most common is the 11778 mutation, accounting for about 50% of all LHON cases. About 45% of the remaining LHON cases are 14484 or 3460. A woman carrying a LHON mutation will pass it to all of her children; men with the LHON gene never pass it to their children. Those who have lost their central vision due to LHON are referred to as “affected;” those with the gene but without vision loss are “carriers.”