Aging & Health A to Z

Cataracts

Causes & Symptoms

The proteins in the lens of your eye gradually change shape and clump together as you age. With time, your lens tissue becomes thicker, less flexible and less transparent. The color of the lens changes too, becoming yellowish as the lens is stained by the protein clumps. Eventually, the discolored lens begins to block the light coming through your pupil. Everything starts to look darker, browner, and less distinct. 

Although aging is the most common basis for these changes, other causes may trigger a cataract, even in young people, producing the following types: 

• Secondary cataracts sometimes form as a result of a chronic illness such as diabetes, after surgery for other eye problems, or from long-term steroid use.
• Traumatic cataracts result from eye injury.
• Congenital cataracts appear in newborn babies or in childhood. They may be caused by a genetic mutation or as a result of an illness in the mother during pregnancy.
• Radiation cataracts may occur after severe exposure to ionizing radiation. 

Risk Factors

Many conditions and lifestyle habits make cataracts more likely to develop. These risk factors include: 

• Aging (the most important risk factor)
• Diabetes
• Drinking too much alcohol
• Excessive exposure to sunlight
• Excessive exposure to ionizing radiation, such as that used in X-rays and cancer radiation therapy
• Family history of cataracts
• High blood pressure
• Obesity
• Previous eye injury or inflammation
• Previous eye surgery
• Prolonged use of corticosteroid medications (such as prednisone)
• Smoking
• Inadequate vitamin intake
• Aging (the most important risk factor).

Symptoms and Warning Signs

Cataracts start slowly and affect only a small part of the lens at first. Therefore, most people have no idea that a cataract is present. Often, only one eye is involved in the beginning. Your ability to see things close up or far away will be affected depending on where the cataract is located. The change may be most obvious at night, or you may notice it more in bright daylight. After months or years, your cataract will grow and cover more of the lens, affecting a greater part of your range of vision.

Common signs and symptoms of cataracts are listed below. But these can also be signs of other eye problems. Any of these warrant a check-up with your eye doctor.

• Cloudy, blurry or dim vision
• Poor night vision; increased difficulty seeing in the dark
• Sensitivity to light and glare; car headlights, lamps, or sunlight seem too bright
• "Halos" appear around lights
• A need to change eyeglass or contact lens prescriptions more often
• Faded or yellowing colors
• Double vision or multiple images in a single eye (this symptom may disappear as the cataract grows). 

Updated: March 2012
Posted: March 2012