A cataract is a clouding of the natural lens inside the eye, just behind the iris centered in the pupil. Contrary to common perception, it is not a ‘film’ on the surface of the eye, although it certainly can cause vision to appear ‘filmy’, among other symptoms.
Cataracts are an inevitable consequence of aging: if you live long enough, you’ll get a cataract. Some general health conditions (like diabetes) and medications (like steroids) can cause cataracts, and longterm exposure to ultraviolet radiation has long been implicated in cataract formation.
