Cataracts

Description

Prognosis

Some cataracts stop progressing after a certain point. Cataracts are never reversible, however, even after eliminating conditions, such as drugs or illnesses, which might have promoted their development. If extensive and progressive cataracts are left untreated they can cause blindness. In fact, cataracts are the leading cause of blindness among adults age 55 and older. About 20.5 million Americans have at least one cataract. By 2020, that number is expected to jump to 30.1 million. More than half of all Americans have a cataract or have had cataract surgery by the time they turn 80.

Fortunately, cataracts nearly always can be successfully removed with surgery. However, surgery is unavailable in certain parts of the world, leaving millions at risk for vision loss. Even in the U.S., where surgery has greatly reduced the risk of blindness, tens of thousands still lose their sight and millions more have poor vision because of cataracts.

Effect on Survival

In a 2001 study, cataracts were associated with a significantly higher mortality rate in older women, although not older men. These higher rates did not seem to be caused by certain health risks (e.g., diabetes) that are often associated with both cataracts and lower survival rates. A 2004 study published by scientists in Italy appears to confirm the association between shortened lifespan and cataracts, especially cataracts confined to the lens nucleus and those that had already required surgery. A few other studies have also linked cataracts and vision impairment with poorer survival, regardless of accompanying health problems. One English study reported that even middle-aged people with cataracts, particularly those in ethnic minority groups, had lower survival rates than their peers, perhaps because of premature aging.

Effect on Survival by Location of the Cataract. Some studies have suggested poorer survival specifically in patients with nuclear or mixed cataracts but not in those with cataracts in the cortex or capsule. Not all studies have found these differences. In any case, nuclear cataracts are highly associated with smoking and diabetes, so they are often signs of declining health, although some studies have found lower survival rates in patients with nuclear cataract regardless of these health risks.

Effect on Driving

A 2001 study concluded that an impaired ability to see contrasts due to cataracts was a specific risk factor for automobile accidents among older drivers. A 2002 study reported twice the rate of automobile accidents in cataract patients who do not have surgery compared to those who had surgery. This finding, however, is obscured by the possibility that patients who choose not to have surgery may have other health problems that put them at risk for accidents. It should also be noted that driving skills decline with age in nearly everyone. Cataract surgery, then, is no insurance against age-related accidents.

Effect on Daily Functioning

Reduced vision ranks third only behind arthritis and heart disease as a cause of impaired function in older people. Extensive cataracts can compromise the ability to earn a living, read, drive, or live independently. Although vision loss has been associated with a number of major adverse effects, few studies have reported on the effect of vision on daily activities.

Both blurred vision and problems in seeing contrasts contribute to impaired activity. The degree of these impairments, however, may have different effects on disability depending on individual tasks and needs. For example, even a slight loss in vision sharpness and contrast can impair the ability to recognize faces or slow down reading speed. For those who read very quickly, this may not be significant, but it could be very disabling for slower readers. In one study, for example, people under 65 rated blurred vision as reducing their quality of life more than any other chronic medical problem except shortness of breath. As mentioned above, in one study, contrast impairment was a specific risk factor for automobile accidents.

Nevertheless some people who have small cataracts can see well enough around the clouded areas to live normally. But for many people, cataracts are extensive enough to interfere greatly with daily activities