Cataract

(kaťah-rakt.) [Gr. kataraktes, a breaking down.] (Hydrog.) A great fall of water over a precipice in the channel of a river, caused by rocks or other obstacles to the course of the stream:-Niagara is a notable example ofa C.-(Surg.) An affection of the crystalline lens of the eye, or its capsule, which becomes so opaque as to prevent the rays of light from pa ing to the optic nerve. It is curable either by depre ing or extracting the lens. [s. 153]