A cataract is a loss of transparency, or clouding, of the
normally clear lens of the eye. As one ages, chemical changes occur in the lens
that make it less transparent. The loss of transparency may be so mild vision
is hardly affected or so severe that no shapes or movements are seen, only
light and dark. When the lens gets cloudy enough to obstruct vision to any significant
degree, it is called a cataract. Glasses or contact lenses cannot sharpen your
vision if a cataract is present.
The most common cause of cataract is aging. Other causes
include trauma, medications such as steroids, systemic diseases such as diabetes
and prolonged exposure to ultraviolet light. Occasionally, babies are born with
Reducing the amount of ultraviolet light exposure by
wearing a wide-brim hat and sunglasses may reduce your risk for developing a
cataract but once developed there is no cure except to have the cataract
surgically removed. Outpatient surgical procedures can remove the cataract
through either a small incision (phacoemulsification) or a large incision
(extracapsular extraction). The time to have the surgical procedure is when
your vision is bad enough that it interferes with your lifestyle.
Cataract surgery is a very successful operation. One and a
half million people have this procedure every year and 95% have a successful
result. As with any surgical procedure, complications can occur during or after
surgery and some are severe enough to limit vision. But in most cases, vision,
as well as quality of life, improves.
Your eye works a lot like a camera. Light rays focus
through your lens on the retina, a layer of light sensitive cells at the back
of the eye. Similar to film, the retina allows the image to be "seen"
by the brain. But over time the lens can become cloudy and prevent light rays
from passing clearly through the lens. This cloudy lens is called a cataract.
The typical symptom of cataract formation is a slow,
progressive, and painless decrease in vision. Other changes include: blurring
of vision; glare, particularly at night; frequent eyeglass prescription change;
a decrease in color intensity; a yellowing of images; and in rare cases, double
Ironically as the lens gets harder, farsighted or
hyperopic people experience improved distance vision and are less dependent on
glasses. However, nearsighted or myopic people become more nearsighted or
myopic, causing distance vision to be worse. Some types of cataracts affect
distance vision more than reading vision. Others affect reading vision more
than distance vision.