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Cataracts:
A cataract is a 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, thus
disrupting normal function.
Hazy or blurred vision may
indicate a cataract.
Cataracts are classified as
one of three types:
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A nuclear cataract is
most commonly seen as it
forms. This cataract
forms in the nucleus,
the center of the lens,
and is due to natural
aging changes.
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A cortical cataract,
which forms in the lens
cortex, gradually
extends its spokes from
the outside of the lens
to the center. Many
diabetics develop
cortical cataracts.
-
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.
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