The cornea is the transparent lining that covers the external front of the eyeball that is the iris and the pupil respectively the colored area that expands and contracts to allow light in and the lens that transmits the light and image to the brain the black center

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The cornea is the transparent lining that covers the external front of the eyeball; that is, the iris and the pupil (respectively, the colored area that expands and contracts to allow light in, and the lens that transmits the light and image to the brain the black center).