Cataracts and macular degeneration are two of the most common eye diseases in the United States. In fact, approximately 17 percent of Americans over the age of 40 have a cataract in either eye, and cataract surgery is the most common surgery in the United States, as well as in other developed countries.
On the other hand, age-related macular degeneration, or AMD, is responsible for more than half of all visual impairment in the United States, and nearly 23 percent of all blindness among Caucasians.
As sobering as these statistics sound, there is hope. Whether you are talking about cataracts or AMD, the key to prevention is probably already sitting right in your refrigerator.
Understanding Eye Disease
A cataract is a clouding of the normally clear lens of the eye. As a cataract forms, the lens becomes more and more yellow and opaque.
While age is one of the largest predictors of cataracts, cataracts can also form after exposure to radiation with X-rays, unprotected exposure to sunlight (think no sunglasses), and long-term corticosterioid use.
Age-related macular degeneration affects the macula, the part of the retina that is responsible for central vision and allows you to see fine details. A person suffering from AMD typically loses central vision, but maintains peripheral vision. For example, they would know that there was a clock on the wall, but they would not be able to tell the time. In this way, AMD has a significant impact on vision, but usually doesn’t cause total blindness.
Like cataracts, aging is a factor in the development of AMD. Other risk factors include smoking and gender, as well as oxidative stress, and a lack of lutein and zeaxanthin in your diet.
Which leads us to …
The Role of Lutein and Zeaxanthin
Lutein and zeaxanthin are carotenoids found in fruits and vegetables. These yellow pigments are antioxidants found within the retina (particularly the fovea, or center of the retina) that help filter out short wavelength blue light.
They have also been shown to help protect against AMD. In a landmark study from the Journal of the American Medical Association, increased intake of lutein and zeaxanthin was strongly associated with a decreased risk for AMD.1
As you age and/or your lifestyle creates more and more free radical damage, which then needs more and more antioxidants to offset the damage, your body (and particularly your eyes) can quickly become deficient in lutein and zeaxanthin.
As a result, your retina cannot filter out the blue light as effectively, making it less able to offset damage from the blue light, and, bingo, you are at increased risk for AMD.
Interestingly, a new study shows that your body has a rather peculiar way of compensating for this lack of yellow pigments (i.e., lutein and zeaxanthin): It forms a cataract!2
Cataracts Help Prevent AMD
Yep, that’s right. One eye “disease” is actually your body’s natural mechanism to protect against an even worse condition.
If you think about it, it makes sense. Lutein and zeaxanthin are yellow pigments that help filter out blue light. In their absence, your body needs to find another yellow substance to do the same job, so it yellows the lens of the eye itself and thickens it in an attempt to protect the retina.
This is why so many researchers have hypothesized that lutein and zeaxanthin help prevent cataracts. The reality, they don’t — not directly anyway. While there is an inverse association between the carotenoids and cataracts, it’s not a direct relationship.3
Instead, what researcher have determined is occurring is that high intake (and, therefore, high retinal concentration) of lutein and zeaxanthin help protect the retina, thereby not only reducing your risk of AMD, but also lessening the need for a cataract to develop in the first place.
Get Those Greens and Yellows and …
Clearly the easiest (and tastiest!) way to help prevent the formation of AMD and cataracts alike is to increase your intake of foods that contain lutein and zeaxanthin. These include green, yellow and orange foods, such as:
- Bell peppers
- Sweet potatoes
- Collard greens
- Egg yolks
Whether you eat them raw or cooked, just eat them. Your eyes will thank you.
1Seddon, JM, et al. Dietary carotenoids, vitamins A, C, and E, and advanced age-related macular degeneration. Eye Disease Case-Control Study Group. JAMA. 1994 Nov 9;272(18):1413-20.
2Wegner, A and Khoramnia, R. Cataract is a self-defence reaction to protect the retina from oxidative damage. Medical Hypotheses. 2011 Feb [Epub ahead of print].
3Vu, HT et al. Lutein and zeaxanthin and the risk of cataract: the Melbourne visual impairment project. Invest Ophthalmol Vis Sci. 2006;47:3783-6.