A cataract is the clouding of the eye’s natural lens, which lies behind the iris and the pupil. This clouding can lead to blurry vision, difficulty with glare, and trouble seeing at night. Cataracts often develop slowly and can affect one or both eyes. They are most commonly associated with aging but can also result from injury, certain diseases, or prolonged exposure to ultraviolet light. Treatment typically involves surgical removal of the cloudy lens and replacement with an artificial intraocular lens.