A cataract is a clouding of
the lens in the eye that affects vision. Most cataracts are
related to aging. Cataracts are very common in older people.
By age 80, more than half of all Americans either have a
cataract or have had cataract surgery. A cataract can occur in either or both eyes. It cannot
spread from one eye to the other.
Causes
The lens lies behind the iris
and the pupil . It works much like a camera lens. It focuses
light onto the retina at the back of the eye, where an image
is recorded. The lens also adjusts the eye's focus, letting
us see things clearly both up close and far away. The lens
is made of mostly water and protein. The protein is arranged
in a precise way that keeps the lens clear and lets light
pass through it. But as we age, some of the protein may
clump together and start to cloud a small area of the lens.
This is a cataract. Over time, the cataract may grow larger
and cloud more of the lens, making it harder to see. Researchers suspect that there are several causes of
cataract, such as smoking and diabetes. Or, it may be that
the protein in the lens just changes from the wear and tear
it takes over the years.
Symptoms
The most common symptoms of a
cataract are:
Cloudy or blurry vision.
Colors seem faded.
Glare. Headlights, lamps, or sunlight may appear too
bright. A halo may appear around lights.
Poor night vision.
Double vision or multiple images in one eye. (This
symptom may clear as the cataract gets larger.)
Frequent prescription changes in your eyeglasses or
contact lenses.
These symptoms also can be a sign of other eye
problems. If you have any of these symptoms, check with
your eye care professional.
Effect on Vision
See our Vision Simulator page on how Cataract can affect
your vision.
Treatment
The symptoms of early cataract
may be improved with new eyeglasses, brighter lighting,
anti-glare sunglasses, or magnifying lenses. If these
measures do not help, surgery is the only effective
treatment. Surgery involves removing the cloudy lens and
replacing it with an artificial lens.
More information
Feel free to download some
materials from our Patient Resource page.
The information above is courtesy of the National Eye Institute, National
Institutes of Health.
