SUMMARY
Leber’s hereditary optic neuropathy (LHON) is a rare genetic mitochondrial disorder that causes blindness in young adults. Typically, it presents with a subacute, painless loss of vision in one eye, followed by the involvement of the other eye in a few weeks to months. It usually leaves permanent visual disability; rarely, partial spontaneous recovery of visual function is possible in some patients. The male to female ratio is estimated at 3:1. In recent years, the drug idebenone was registered for supportive pharmacological treatment possibly leading to partial vision improvement. Due to its rare nature, the disorder often remains misdiagnosed or undiagnosed. In this article, we present four clinical cases which, after an extensive and long-lasting diagnostics, unveiled themselves as LHON. In the Slovenian database of rare eye disorders that has been kept since 1996, the prevalence of LHON is 1/72000. When suspected, the family history of poor eyesight in the maternal line, genetic testing, and referral to a tertiary institution are crucial for confirmation and treatment.