Below is an instruction from Human. Write a response.
    ### Instruction:
    What are the symptoms of Leber hereditary optic neuropathy ?
    ### Response:
    What are the signs and symptoms of Leber hereditary optic neuropathy? Blurring and clouding of vision are usually the first symptoms of this disorder. These vision problems may begin in one eye or simultaneously in both eyes; if vision loss starts in one eye, the other eye is usually affected within several weeks or months.
    