What is Leber's or 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.


What causes Leber's or LHON?


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. 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 a LHON mutation gene but without vision loss are “carriers.”


 Diagnosis of Leber's or LHON?


Because there is a clear pattern of LHON inheritance, those with a family member on the maternal inheritance chain with LHON should expect that any sudden, painless central vision loss is caused by LHON.  However, carrying the LHON mutation does not mean that a LHON carrier will lose central vision; most who carry the mutation do not.