Age-related macular degeneration (AMD) is the leading cause of blindness among people of European descent over 65 years. And cataracts are the leading cause of vision loss in the US.

AMD occurs when the macula (part of the retina located at the back of the eye) starts to deteriorate, causing a gradual loss of vision. A cataract is a clouding of the eye’s lens that results in diminished vision or loss of vision. Both commonly occur as a result of aging.

Many studies have looked at the prevalence of these two conditions among different populations, but until now all have been too small or too focused on one region to estimate the prevalence among the whole US population.

This article will examine two new studies that were part of a series of studies on blindness and aging in the April 2004 issue of Archives of Ophthalmology. One study found that more than 1.75 million Americans have AMD and predicted that this number will increase to almost 3 million by 2020. The other study estimated that 20.5 million Americans over 40 currently have cataracts, and predicted that this number will increase to 30.1 million by 2020.

About the Studies

The Eye Diseases Prevalence Research Group conducted both of these studies by analyzing the collective findings of several large, population-based studies from the past 20 years. To estimate the current prevalence of AMD and cataracts in the US, they applied the prevalence rates from the studies to the 2000 US census data. To predict the increases of these conditions they used the projected US population figures for 2020.

The Findings

The study looking at AMD found that overall, an estimated 1.5% of Americans over age 40 have AMD. Additionally they found:

  • The prevalence of AMD increased significantly with age
  • More than 15% of white women over 80 years of age have AMD
  • AMD is more common among white than black people

The researchers predict that the number of Americans over 40 with AMD will increase by 50% to almost three million by 2020.

The study focusing on cataract prevalence found that overall, an estimated 17% of Americans over 40 have a cataract in either eye. They also found:

  • The prevalence of cataracts increased with age
  • More women than men are affected by cataracts in the US
  • Cataracts were more prevalent among white men than black men

The researchers predict that by 2020, 30.1 million Americans over 40 will be affected by cataracts.

A limitation of these studies is that they did not include data on people of Asian descent, and there was only limited data for Hispanics and blacks. It’s also important to point out that the future predictions of cataract and AMD prevalence are based on the assumption that these conditions will continue to occur at the same rate.

How Does This Affect You?

Vision impairments, if severe enough, often mark the end of an individual’s independent functioning, not to mention the loss of one of life’s greatest pleasures. These findings suggest that many Americans will be affected by age-related vision loss as they grow older. These predictions have significant implications for aging baby boomers, as well as future health care resources in the US.

The most common type of AMD is known as dry AMD. Currently there is no treatment for this type of AMD. Wet AMD, while accounting for only 10% of cases, is responsible for 90% of AMD related blindness. Fortunately, there is surgery that can treat this form of AMD if caught early on.

Cataracts, on the other hand, are treatable with surgery. Currently there are 1.5 million cataract surgeries done in the US each year and up to 60% of all Medicare costs related to vision are due to cataract surgery. But as cataracts affect more people, Medicare will certainly struggle to cover these costs. Additionally, the increased need may lead to a waiting period to have the procedure done.

Aside from age, known risk factors for cataracts include: exposure to UV-B radiation from sunlight, a family history of cataracts, and diabetes. Wearing sunglasses that effectively filter out UV-B rays, therefore, may reduce your risk of developing cataracts. Known risk factors for AMD include: being female, white ethnicity, smoking, and a family history of AMD. There is some research to suggest that taking certain vitamins may decrease the risk of vision loss from AMD, but not enough is known yet. If you are over age 60 you should have your eyes checked at least once every two years for both of these conditions.