A cataract forms when the lens in the eye becomes cloudy and reduces visual clarity. The National Eye Institute (NEI) reports that the retina cannot receive a clear picture through the cataract, which results in blurry vision. There are a number of factors related to the cause of cataracts, including aging, injury and genetics. Cataracts develop in one or both eyes but cannot spread from one to the other.
Aging
The most common cause of cataracts is aging. The NEI reports that nearly 50 percent of all Americans will have cataracts by the time they turn 80. Protein gathers over the lens and clumps together over the years, creating a cataract. Over time, the protein gets thicker, and the cataract becomes more difficult to see behind. Researchers at the NEI are not certain whether the lens becomes cloudy from normal wear and tear or if lifestyle factors such as diet and smoking play a much larger role in the development of cataracts in the elderly.
Surgery
After the initial cataract surgery is performed to remove the cloudy lens, the new lens also will become blurry over time because it is held in place by the original shell, report doctors at the Windsor Laser Eye Institute. Most people who have had cataract surgery can expect to return for another procedure about every 10 years to remove the secondary cataracts. Secondary cataracts also can form following other eye surgeries, such as a procedure to treat glaucoma.
Trauma
Cataracts can form as a result of an eye injury, even years after the accident took place. Doctors at the University of Iowa report that when vision is affected immediately, surgery can be performed to remove the blurry lens and replace it. Traumatic cataracts are not always recognized because they often occur as the person ages and forgets about the injury. Other trauma that can cause cataracts is exposure to radiation. People who work in X-ray labs or use tanning beds should be extra careful about exposing their eyes to harmful rays that can add to the risk of developing cataracts later in life. People with diabetes often form cataracts as a side effect of the disease. Additionally, the NEI reports that steroid use has been linked to cataracts as well.
Congenital
The NEI reports that some babies are born with cataracts. The cloudy eye lenses also can develop during early childhood and usually appear in both eyes. Since babies cannot report the lack of vision, they typically go unreported. Baby cataracts are so small that they are difficult to gauge as well. Usually congenital cataracts are discovered when the child reaches school age and receives an eye examination and referral to an optometrist.
