Vision loss, and the resulting loss of quality of life, is all too common: Cataracts affect more than half of all Americans over age 80, and as many as 11 million Americans have some form of macular degeneration. In the past decade, research has pointed to nutrition as one of the factors that might reduce the risk and slow the progression of these disorders.
WHAT ARE CATARACTS AND
HOW DO THEY FORM?
Light enters the eye through the pupil, the round,
black opening at the center of the iris. Behind the pupil is the lens, which
catches the incoming light and focuses it onto the retina at the back of the
A cataract is formed when protein fibers in the
lens change shape and clump together, clouding the normally transparent lens.
This is similar to the process that turns the protein in egg albumin from clear
to white when cooked. In fact, most well-developed cataracts look milky white,
although in some cases, the lens can turn yellow or brown instead.
Cataracts develop slowly, over a period of years.
But even before a cataract can be seen from the outside, vision can become
blurry or cloudy — like looking through a fogged windshield. Other
possible symptoms include worsened night vision, faded color vision, and
starburst or halo effects around bright lights. Because cataracts can be
surgically removed, these symptoms are only temporary — after surgery
you may need glasses to see detail, but your sight will be clear.
No one knows exactly what causes eye proteins to
clump and create a cataract. Many scientists blame unstable molecules known as
free radicals, which can wreak havoc throughout the body, causing destruction
and disease wherever they go through a complex chemical process called
oxidative stress. And what creates free radicals? Well ... the single greatest
cause is just being alive. Natural metabolic processes from normal body functions
like breathing and digesting food generate lots of free radicals, and unless
they are neutralized, they build up over time. (A powerful tool to neutralize
free radicals are antioxidants; learn more in How Food Affects Cataracts. That's
why our bodies seem to deteriorate slowly with age — it's the
accumulated damage from years of free radical attacks.
Two other major causes of free radicals are smoking
and ultraviolet radiation from sunlight. This is the reason all cataract-prevention
strategies must include a commitment to stop smoking and reduce exposure to
sunlight. Cataracts can also be caused by surgery for other eye problems,
traumatic eye injury, or long-term use of corticosteroids. In very rare
circumstances, genetic anomalies can create cataracts in newborn babies or
WHAT IS MACULAR
DEGENERATION AND HOW DOES IT OCCUR?
The retina is the part of the eye that receives
light and images from the world and sends them to the optic nerve to be
processed in the brain. The macula is the center of the retina —
and the most sensitive part. It fine-tunes focus at the center of our visual
field, the area that allows us to recognize faces, read words on a page, and
discern detail in anything we look at. Macular degeneration, then, is a
deterioration of the macula, gradually leading to central blindness. Peripheral
vision remains clear, so it isn't a total lack of sight but the loss of
There are two types of macular degeneration: dry
(also called atrophic), caused by a gradual breakdown of light receptors; and
wet (also called exudative), caused by leaks in the blood vessels of the
retina, which in turn cause scarring and tissue death. With both types, people
usually notice vision distortions first, such as straight lines appearing wavy,
along with difficulty reading and recognizing faces. As more and more receptors
die, central vision disappears. Fortunately, major advances have been made in
treating the wet form of macular degeneration. For example, doctors can now
prescribe injectable drugs that stop the leaky blood vessels from growing.
There is currently no medical treatment for dry macular degeneration.
Macular degeneration happens most often in people
over age 70, primarily women. Although it can run in families, no one knows
what causes macular degeneration, or how to stop it once it begins.