A cataract is a clouding of the eye's natural lens, which lies behind the iris and the pupil. The lens works much like a camera lens, focusing light onto the retina at the back of the eye. The lens also adjusts the eye's focus, letting us see things clearly both up close and far away.
The lens is mostly made up of water and protein. The protein is arranged in a precise way that keeps the lens clear and lets light pass through it. But as we age, some of he protein may clump together and start to cloud a small area of the lens. This is cataract, and over time, it may grow larger and cloud more of the lens, making it harder to see.
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. 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.
When symptoms begin to appear, you may be able to improve your vision for a while using new glasses, strong bifocals, magnification, appropriate lighting or other visual aids. Surgery is an option once cataracts have progressed enough to seriously impair your vision and affect your daily life.