All About Cataracts

Smoking is associated with increased risk of cataracts among Malaysian adults, with nearly 20 percent of nuclear cataracts in Malay men attributable to smoking.

Smoking increases cataract risk, study finds.

That’s the conclusion of a new study published in this month’s issue of Archives of Ophthalmology.

Researchers in Singapore evaluated 2,927 Malaysian adults ages 40 to 80 who underwent comprehensive eye exams that included lens photographs. Among this study population, 1,338 (45.7 percent) had cataracts.

After adjusting for age, sex and other factors, current smokers were 48 percent more likely to have cataracts. The association between smoking and cataracts was strongest for nuclear cataracts; current smokers were twice as likely as nonsmokers to have this type of cataract.

Nuclear cataracts are the most common type of cataracts associated with aging. These opacities develop in the center of the lens and initially can induce myopia, resulting in a temporary improvement in reading vision sometimes referred to as “second sight.” Unfortunately, “second sight” disappears as the cataract continues to grow.

Among the study participants, 43.5 percent of men currently smoked, compared with only 3.2 percent of women.

Analysis of the study data also revealed that two indicators of low socioeconomic status — low education and low monthly income — also were associated with greater risk for nuclear cataracts in this sample population.

Women who have undergone hormone replacement therapy after menopause may have  a higher risk of developing cataracts, according to a new study.

Researchers in Sweden conducted an eight-year prospective study of more than 30,000 post-menopausal women to evaluate the effect of hormone replacement therapy (HRT) on the development of cataracts and the need for cataract surgery.

Among the study population, more than 4,300 cataract removal procedures were performed between 1997 and 2005.

The researchers found that the risk for cataract surgery was 14 percent higher among women who had undergone HRT in the past and 18 percent higher in women who were currently using HRT, compared with women who never used HRT.

Women who used hormone replacement therapy for longer durations had higher cataract risks than those who used HRT for shorter periods. Women undergoing HRT for more that 10 years had a 20 percent greater risk of needing cataract surgery, compared with those who never used HRT, according to the study.

Also, alcohol consumption appears to be an added risk factor for cataracts among women using HRT. Women currently undergoing HRT who reported having more than one alcoholic drink per day had a 42 percent increased risk of cataract surgery, compared with non-drinking women who never used HRT.

Smoking was not found to significantly increase cataract risk for women using HRT in the study.

The researchers concluded that post-menopausal women using hormone replacement therapy for a significant period of time may have an increased risk of cataracts and cataract surgery, especially women using HRT who drink an average of more than one alcoholic drink per day.

A full report of the study appears in the March 2010 issue of Ophthalmology, the official journal of the American Academy of Ophthalmology.

People with cataracts appear to have a higher risk for cardiovascular disease, according to a new study published in Eye, the official journal of The Royal College of Ophthalmologists.

Researchers conducted a retrospective study of 12,984 patients over age 50 who underwent cataract surgery in the Central District of Clalit Health Services in Israel during the period 2000 to 2007, comparing their health with 25,968 age- and gender-matched controls.

All subjects were evaluated for cardiovascular disease (CVD) and CVD risk factors, including carotid artery disease, peripheral vascular disease, high blood pressure, chronic renal failure, ischemic heart disease, congestive heart failure, diabetes, smoking, alcohol abuse and high cholesterol.

Results of the study showed that risk factors for cardiovascular disease  were significantly more prevalent in patients undergoing cataract surgery than among people of the same age and gender who did not have cataracts.

The researchers also found a significant association of the following conditions with the development of cataracts: diabetes, smoking, high cholesterol, high blood pressure, carotid artery disease, peripheral vascular disease, ischemic heart disease  and chronic renal failure.

The study was published online on March 26, 2010 on the website www.nature.com/eye.

Ed. note:  The findings of this study suggest you may be able to lower your risk of cataracts and the need for cataract surgery by adopting a healthy lifestyle and avoiding known risk factors for cardiovascular disease.

Cataracts are a common cause of vision loss in older adults.

In 2004, the Eye Diseases Prevalence Research Group (EDPRG), estimated that 20.5 million Americans (17.2 percent) over age 40 had a cataract in either eye, and 6.1 million (5.1 percent) already had a cataract removed. And according to the National Eye Institute (NEI), by age 80, more than half of all Americans either have a cataract or have had cataract surgery.

But, besides advancing age, are there other risk factors associated with the development of cataracts?

A large study of 3,721 adults in Australia found the following additional risk factors for cataracts:

•  Women are more likely than men to develop cortical cataracts. (This was also true in the American study by EDPRG, which found that women are almost 40 percent more likely than men to develop cataracts.)
• Working as a laborer (compared to having a white-collar occupation) and myopia also are risk factors associated with cortical cataracts.
• Cigarette smoking and a history or arthritis are associated with the development of nuclear cataracts.
• Diabetes and taking calcium channel blockers (medications commonly used to treat high blood pressure) for more than five years are risk factors associated with posterior subcapsular cataracts.

It is likely that in the United States, there will be an increase in diabetes-related cataracts in the future. According to the Centers for Disease Control and Prevention, 34 percent of Americans over age 20 are obese, and obesity is a primary risk factor for Type 2 diabetes. Currently, 24 million Americans (8 percent) have known diabetes, and an estimated 57 million (19 percent) have “pre-diabetes,” meaning they have blood glucose levels that are higher than normal but not yet high enough to be diagnosed as diabetes.

Some researchers believe that by the year 2050, the number of diabetes-related cataracts will increase by over 200 percent. Also, the number of Americans with diabetic retinopathy (another vision-threatening complication of diabetes) is expected to increase from 1.2 million to 3.4 million over the same period. 

The take-home message: If you want to lower your risk for cataracts, two steps you can take are to avoid or quit smoking and, if you are overweight or have pre-diabetes, to consult with your doctor and begin a diet and exercise program to lower your risk of diabetes.

Sources:

1. Prevalence of cataract and pseudophakia/aphakia among adults in the United States. Archives of Ophthalmology. April 2004.
2. Development of cataract and associated risk factors: The Visual Impairment Project. Archives of Ophthalmology. January 2006.
3. Diabetes and obesity: A challenge for every ophthalmologist. Archives of Ophthalmology. March 2009.