All About Cataracts

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.

People with diabetes who undergo cataract surgery have twice the risk of progression of their diabetic retinopathy, according to a new study.

Researchers at the University of Sydney (New South Wales, Australia) and the University of Melbourne (Victoria, Australia) followed 190 diabetic patients age 65 and older who underwent phacoemulsification cataract surgery between 2004 and 2006. Of the 190 patients, 169 were followed for at least 12 months after surgery.

During the 12-month follow-up period, diabetic retinopathy (DR) developed in 28.2 percent of eyes that underwent cataract surgery with intraocular lens (IOL) implantation and did not have DR prior to surgery. During the same 12-month period, diabetic retinopathy developed in 13.8 percent of eyes that did not undergo cataract surgery and did not have DR at the beginning of the study period.

In a paired-eye comparison of 45 patients with pre-existing diabetic retinopathy who had cataract surgery in one eye but not the other and were at risk of DR progression, 35.6 percent of the post-surgical eyes exhibited progression of diabetic retinopathy, compared with 20 percent of the fellow eyes that did not undergo surgery.

The researchers concluded that people with diabetes who undergo modern phacoemulsification cataract surgery appear to have twice the risk of developing diabetic retinopathy or experiencing a progression of their DR  12 months after surgery.

This added risk, however, is lower that the risk of diabetes-related cataract surgery complications that has been previously documented in diabetic patients who have undergone less advanced cataract surgery (“intracapsular” and “extracapsular” cataract surgery without phacoemulsification).

Source: Development and progression of diabetic retinopathy 12 months after phacoemulsification cataract surgery. Ophthalmology. August 2009.

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.