Cataracts
Information
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Cataract
Symptoms and Signs
What Causes Cataracts?
Cataract Treatment
A cataract is the clouding of the
eye's natural lens, which lies behind the iris and the pupil. The lens works
much like a camera lens, focusing light onto the retina at the back of the eye.
The lens also adjusts the eye's focus, letting us see things clearly both up
close and far away.
The lens is mostly made of 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, and over time, it may grow larger and cloud more of the lens, making
it harder to see.
Researchers are gaining additional
insights about what causes these specific types of proteins (crystallins) to cluster in abnormal ways to cause lens
cloudiness and cataracts. One recent finding suggests that fragmented versions
of these proteins bind with normal proteins, disrupting normal function.
Cataracts are classified as one of
three types:
- A
subcapsular cataract begins at the
back of the lens. People with diabetes, high farsightedness, retinitis pigmentosa or those taking high doses of steroids may
develop a subcapsular cataract.
- A
nuclear cataract is most commonly seen as it forms. This cataract
forms in the nucleus, the centre of the lens, and is due to natural aging
changes.
- A
cortical cataract, which forms in the lens cortex, gradually
extends its spokes from the outside of the lens to the centre. Many
diabetics develop cortical cataracts.
Cataract
Symptoms and Signs
Hazy or
blurred vision may indicate a cataract.
A cataract starts out small and at
first has little effect on your vision. You may notice that your vision is
blurred a little, like looking through a cloudy piece of glass or viewing an
impressionist painting.
A cataract may make light from the
sun or a lamp, seem too bright or glaring. Or you may notice when you drive at
night that the oncoming headlights cause more glare than before. Colors may not
appear as bright as they once did.
The type of cataract you have will
affect exactly which symptoms you experience and how soon they will occur. When
a nuclear cataract first develops, it can bring about a temporary improvement
in your near vision, called "second sight." Unfortunately, the
improved vision is short-lived and will disappear as the cataract worsens. On
the other hand, a subcapsular cataract may not
produce any symptoms until it's well-developed.
If you think you have a cataract, see
an eye doctor for an exam to find out for sure.
What
Causes Cataracts?
No one knows for sure why the eye's
lens changes as we age, forming cataracts. Researchers are gradually
identifying factors that may cause cataracts — and information that may help to
prevent them.
Many studies suggest that exposure to
ultraviolet light is associated with cataract development, so eyecare practitioners recommend wearing sunglasses and a
wide-brimmed hat to lessen your exposure.
Other types of radiation may also be
causes. For example, a 2005 study conducted in
Other studies suggest people with
diabetes are at risk for developing a cataract.
The same goes for users of steroids,
diuretics and major tranquilizers, but more studies are needed to distinguish
the effect of the disease from the consequences of the drugs themselves.
Some eyecare
practitioners believe that a diet high in antioxidants, such as beta-carotene
(vitamin A), selenium and vitamins C and E, may forestall cataract development.
Meanwhile, eating a lot of salt may increase your risk.
Other risk factors include cigarette
smoke, air pollution and heavy alcohol consumption.
A small study published in 2002 found
lead exposure to be a risk factor; another study in December 2004, of 795 men
age 60 and older, came to a similar conclusion.
But larger studies are needed to
confirm whether lead can definitely put you at risk and, if so, whether the
risk is from a one-time dose at a particular time in life or from chronic
exposure over years.*
Cataract Treatment
When symptoms begin to appear, you
may be able to improve your vision for a while using new glasses, strong
bifocals, magnification, appropriate lighting or other visual aids.
An intraocular lens (IOL) is implanted in the eye in place of the clouded
natural lens. Shown is an IOL which filters out blue light, which may be
harmful to eyes.
Think about surgery when your
cataracts have progressed enough to seriously impair your vision and affect
your daily life. Many people consider poor vision an inevitable fact of aging,
but cataract surgery is a simple, relatively painless procedure to regain
vision.
Cataract surgery is very successful
in restoring vision. In fact, it is the most frequently performed surgery in
the
During surgery, the surgeon will
remove your clouded lens and in most cases replace it with a clear, plastic
intraocular lens (IOL).
New IOLs
are being developed all the time to make the surgery less complicated for
surgeons and the lenses more helpful to patients. Presbyopia-correcting
IOLs potentially help you see at all distances, not
just one. Another new type of IOL blocks both ultraviolet and blue light rays,
which research indicates may damage the retina.
Read more about what to expect if you
have cataract surgery and how to deal with rare cataract surgery complications.
Also, men should be aware that certain prostate drugs can cause intraoperative floppy iris syndrome (IFIS) during a
cataract procedure.