Below is an instruction from Human. Write a response.
    ### Instruction:
    How to diagnose Cone dystrophy ?
    ### Response:
    How is cone dystrophy diagnosed? The diagnosis of cone dystrophy is made based upon the presence of characteristic symptoms, a detailed family history, a thorough clinical evaluation and a number of supporting tests. While exams that measure visual acuity, perception of color, and field of vision are used to arrive at a proper diagnosis, an electroretinogram (ERG) is used to confirm the diagnosis.
    