Cataracts are a condition where the lens (the part of the eye that focuses light) becomes cloudy. The lenses in the eyes are normally clear or transparent, but with age, the structure or chemical makeup of the lenses changes, causing them to "cloud over." This causes a gradual and painless loss of vision, which can eventually lead to blindness. Fortunately, the process can almost always be reversed with surgery.
Cataracts are very common. They usually begin to appear after age 50, and about half of people aged 75 are affected. While we're all at risk of getting them as we age, some things make cataracts more likely, including cigarette smoking, lack of vitamins, sun exposure, and certain medications (see below).
The lenses of your eyes are mostly made up of neatly arranged proteins. Sometimes these proteins stick together, breaking formation and losing transparency. This causes the lenses to become cloudy. The world becomes hazy, darker, and less colorful. Untreated, the cloudy area may spread, progressively impairing vision in that eye.
A few people are born with congenital cataracts, which usually affect both eyes. These don't always affect vision. Traumatic cataracts refer to a condition that may appear immediately following an eye injury, or it may occur years later. Secondary cataracts are caused by certain chronic diseases. Diabetes is the most common cause of secondary cataracts.
Aging is the most common cause of cataracts. These cataracts are called senile cataracts.
The following factors can add to the risk of developing cataracts:
- Exposure to sunlight increases the risk of senile cataracts. Radiation from the sun, especially ultraviolet B (UVB) rays, damages the proteins in the lens.
- Cigarette smoke damages the proteins in the lens.
- Lack of some vitamins and other antioxidants such as vitamins C and E, selenium, beta-carotene, and lycopene has been shown by research to be linked to cataracts. Antioxidants protect the body from oxidants, also known as free radicals. Free radicals react with your cells, effectively "rusting" them. If you're not getting enough antioxidants in your diet, such as vitamins C and E, you might be putting yourself at risk for cataracts.
Certain medications can also cause cataracts, including:
- chlorpromazine*, a sedative
- amiodarone, a heart medication
- phenytoin, an antiseizure medication used in epilepsy
- lovastatin, a cholesterol-lowering medication
- corticosteroids such as prednisone that are used to reduce inflammation