A cataract is a clouding or opaque area over the lens of the eye - an area that is normally transparent. As this thickening occurs, it prevents light rays from passing through the lens and focusing on the retina - the light sensitive tissue lining located in the back of the eye. This clouding is caused when some of the protein which makes up the lens begins to clump together and interferes with vision.
In its early stages, a cataract may not cause a problem. The cloudiness may affect only a small part of the lens. However, the cataract may grow larger over time and affect more of the lens, making it harder to see. As less light reaches the retina, it becomes increasingly harder to see and vision may become dull and blurry. While cataracts cannot spread from one eye to another, many persons develop cataracts in both eyes.
Did You Know?
The word "cataract" literally means "waterfall." For persons with an advanced cataract that covers a large portion of the eye lens, vision can be described as trying to see through a waterfall.