Feb 14, 2014: 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 allows light to 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.
Most cataracts occur gradually as we age and don’t become bothersome until after age 55.
However, cataracts can also be present at birth (congenital cataracts) or occur at any age as
the result of an injury to the eye (traumatic cataracts). Cataracts can also be caused by
diseases such as diabetes or can occur as the result of longterm use of certain medications,
such as steroids.
Cataract signs and symptoms
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. However, as cataracts worsen, you are likely to notice some or all of
• Blurred vision that cannot be corrected with a change in your glasses prescription.
• Ghost images or double vision in one or both eyes.
• Glare from sunlight and artificial light, including oncoming headlights when driving at
• Colors appear faded and less vibrant.
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 gathering
information that may help to prevent them.
Many studies suggest that exposure to ultraviolet light is associated with cataract
development, so eye care practitioners recommend wearing sunglasses and a widebrimmed
hat to lessen your exposure. Other types of radiation may also be causes. For example, a
study conducted in Iceland suggests that airline pilots have a higher risk of developing a
nuclear cataract than nonpilots, and that the cause may be exposure to cosmic radiation. A
similar theory suggests that astronauts, too, are at greater risk of cataracts due to their higher
exposure to cosmic radiation.
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. Other
risk factors for cataracts include cigarette smoke, air pollution and heavy alcohol
When symptoms of cataracts begin to appear, you may be able to improve your vision for a
while using new glasses, stronger bifocals and greater light when reading. But when these
remedies fail to provide enough benefit, it’s time for cataract surgery. Cataract surgery is very
successful in restoring vision. In fact, it is the most frequently performed surgery in the United
States, with nearly 3 million cataract surgeries done each year. More than 90% of people who
have cataract surgery regain very good vision, somewhere between 20/20 and 20/40, and
sightthreatening complications are relatively rare.
During surgery, the surgeon will remove your clouded lens and 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. Presbyopiacorrecting
IOLs not only improve your distance vision, but can decrease your reliance on reading
glasses as well.
If you need cataracts removed from both eyes, surgery usually will be done on only one eye
at a time. An uncomplicated surgical procedure lasts only about 10 minutes. However, you
may be in the outpatient facility for 90 minutes or longer because extra time will be needed for
preparation and recovery.