Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Leber hereditary optic neuropathy ?
    ### Response:
    Leber hereditary optic neuropathy (LHON) is an inherited form of vision loss. Although this condition usually begins in a person's teens or twenties, rare cases may appear in early childhood or later in adulthood. For unknown reasons, males are affected much more often than females.
    