A cataract is NOT a film nor a growth on the top of the eye. When that lens becomes cloudy or opaque, sharp vision is no longer possible. Cataracts are not contagious. They can not spread beyond the lens nor harm the eye or any other parts of the body. Cataracts cannot be prevented nor can their progress be stopped or reversed.
Cataracts usually develop with age just like gray hair.
They are caused by a decrease in normal protein structures within the eye as you age, and there is no known way to prevent this from happening. Cataracts can also possibly be caused by glaucoma, high blood pressure, kidney disease, diabetes, or trauma to the head. Because each person's body and system is different, it is difficult to predict just how quickly your cataract may develop. In some people, the clouding proceeds at a rate rapid enough to cloud the eye's vision in only several months. For others, it may take several years.