Patients with LHON mitochondrial DNA mutations usually do not have any symptoms until early in adult life, when a “trigger” leads to acute loss of vision. What these triggers are and what causes them is still unclear, however, and there remain critical unanswered questions about LHON, such as;

  • why does visual loss most often occur during the second and third decade of life?
  • what causes such a sudden loss of vision over weeks or months?
  • why do a small number of patients recover their vision?

Work in this area is being carried out at the Ottawa Eye Hospital along with other research institutes.

Answering these questions and understanding the triggers that precipitate LHON is fundamental to developing treatment options.

Most experts seem to agree that it is sensible to avoid smoking and excessive alcohol intake if you are a carrier of one of the LHON mutations or affected by vision loss.

Some drugs are known to have the potential to cause damage to mitochondria. As both carriers and those affected by LHON are known to have weaknesses in their mitochondria, it makes sense to understand and if possible to limit the use of these drugs where alternatives exist.

It may be helpful to review the list of medications on the Mito Action website ( with your GP before making these decisions: