Trauma cataract. Close-up of the eye of a patient with a cataract caused by a foreign body embedded in the lens (known as a trauma cataract). The grey mass of the cataract can be seen obscuring the pupil of the eye. A cataract describes the obscuring of vision due to loss of lens transparency. Aging is the most common cause, where the lens gradually loses transparency over time. However, foreign bodies (such as in this case), radiation, diseases such as diabetes, and drugs such as steroids are other causes. Congenital cataracts are rare. Surgery is an effective treatment.