A cataract is a clouding of the eye's natural lens, which lies behind the iris and the pupil. Cataracts are the most common cause of vision loss in people over age 40 and is the principal cause of blindness in the world Symptoms: A cataract starts out small and at first has little effect on your vision. You may notice that your vision is blurred a little, like looking through a cloudy piece of glass or viewing an impressionist painting. A cataract may make light from the sun or a lamp seem too bright or glaring. Or you may notice when you drive at night that the oncoming headlights cause more glare than before. Colors may not appear as bright as they once did. Besides advancing age, cataract risk factors include, Ultraviolet radiation from sunlight and other sources, Diabetes, Hypertension, Obesity, Smoking, Prolonged use of corticosteroid medications, Statin medicines used to reduce cholesterol, Previous eye injury or inflammation, Previous eye surgery, Hormone replacement therapy, Significant alcohol consumption, High myopia, Family history.