Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Dry Eye ?
    ### Response:
    There are two types of dry eye: aqueous tear-deficient dry eye and evaporative dry eye. Aqueous tear-deficient dry eye is a disorder in which the tear glands do not produce enough of the watery component of tears to maintain a healthy eye surface, called the cornea.
    