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 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 the protein may clump together and start to cloud a small area of the lens. This is a cataract, and over time, it may grow larger and cloud more of the lens, making it harder to see.

Researchers are gaining additional insights about what causes these specific types of proteins (crystallins) to cluster in abnormal ways to cause lens cloudiness and cataracts. One recent finding suggests that fragmented versions of these proteins bind with normal proteins, disrupting normal function.

One form of cataract is a cortical cataract, which forms in the lens cortex, gradually extends its spokes from the outside of the lens to the center. Many diabetics develop cortical cataracts.Third is subcapsular cataract begins at the back of the lens.

People with diabetes, high farsightedness, retinitis pigmentosa or those taking high doses of steroids run the risk of developing a subcapsular cataract. Congenital cataracts are known to be caused by infections women get during pregnancy, such as rubella.

Cataracts have also been connected with metabolic deficiencies such as galactosemia. Congenital cataracts risk factors include is inherited metabolic diseases, history of family or genetic cataracts, and also with infections due to pregnancy.

No one knows for sure why the eye’s lens changes as we age, forming cataracts. Researchers are gradually identifying factors that may cause cataracts – and information that may help to prevent them. Many studies suggest that exposure to ultraviolet light is associated with cataract development, so eyecare practitioners recommend wearing sunglasses and a wide-brimmed hat to lessen your exposure.

Other types of radiation may also be causes. For example, a 2005 study conducted in Iceland suggests that airline pilots have a higher risk of developing nuclear cataract than non-pilots and that the cause may be exposure to cosmic radiation. A similar theory suggests that astronauts, too, are at risk from cosmic radiation.

Think about surgery when your cataracts have progressed enough to seriously impair your vision and affect your daily life. Many people consider poor vision an inevitable fact of aging, but cataract surgery is a simple, relatively painless procedure to regain vision.