Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Cataract ?
    ### Response:
    A Clouding of the Lens in the Eye A cataract is a clouding of the lens in the eye that affects vision. The lens is a clear part of the eye that helps to focus light, or an image, on the retina. The retina is the light-sensitive tissue at the back of the eye.
    