This is a thickening of the lens in the eye, causing it to block light. The symptoms are cloudy vision. In babies and children, a cataract is a rare but important cause of reduced vision. Cataracts may not cause symptoms in a child, and may only be noticed because of a squint. They can be diagnosed by a careful vision test and eye examination. Treatment of most cataracts is surgical. It usually involves removal of the cataract and insertion of a plastic lens implant.