A cataract is a disease of the eye lens, regardless of
the cause; the normally clear lens becomes opaque and light transmission
and perception are reduced. Congenital cataracts occur especially in children
born to mothers who have had rubella in
early pregnancy, and in a number of inherited
disorders. Certain disturbances of metabolism or hormone production can cause cataracts,
especially diabetes. Eye trauma
and inflammation are other causes in
adults. Some degree of cataract formation is common in old age. It is among
the commonest causes of blindness in developed
Types of cataract
Although most cataracts are related to aging, there are other types of cataract:
- Secondary cataract. Cataracts can form after surgery
for other eye problems, such as glaucoma.
Cataracts also can develop in people who have other health problems,
such as diabetes. Cataracts are sometimes linked to steroid use.
- Traumatic cataract. Cataracts can develop after an
eye injury, sometimes years later.
- Congenital cataract. Some babies are born with cataracts
or develop them in childhood, often in both eyes. These cataracts may
be so small that they do not affect vision. If they do, the lenses may
need to be removed.
- Radiation cataract. Cataracts can develop after exposure
to some types of radiation.
How cataracts affect vision
Age-related cataracts can affect your vision in two ways:
- Clumps of protein reduce the sharpness of the image reaching the retina.
The lens consists mostly of water and protein. When the protein clumps
up, it clouds the lens and reduces the light that reaches the retina.
The clouding may become severe enough to cause blurred vision. Most
age-related cataracts develop from protein clumpings.
When a cataract is small, the cloudiness affects only a small part of
the lens. You may not notice any changes in your vision. Cataracts tend
to "grow" slowly, so vision gets worse gradually. Over time, the cloudy
area in the lens may get larger, and the cataract may increase in size.
Seeing may become more difficult. Your vision may get duller or blurrier.
- The clear lens slowly changes to a yellowish/brownish color, adding
a brownish tint to vision.
As the clear lens slowly colors with age, your vision gradually may
acquire a brownish shade. At first, the amount of tinting may be small
and may not cause a vision problem. Over time, increased tinting may
make it more difficult to read and perform other routine activities.
This gradual change in the amount of tinting does not affect the sharpness
of the image transmitted to the retina.
If you have advanced lens discoloration, you may not be able to identify
blues and purples. You may be wearing what you believe to be a pair
of black socks, only to find out from friends that you are wearing purple
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.
A cataract needs to be removed only when vision loss interferes with your
everyday activities, such as driving, reading, or watching TV. You and your
eye care professional can make this decision together. Once you understand
the benefits and risks of surgery, you can make an informed decision about
whether cataract surgery is right for you. In most cases, delaying cataract
surgery will not cause long-term damage to your eye or make the surgery
more difficult. You do not have to rush into surgery.
Sometimes a cataract should be removed even if it does not cause problems
with your vision. For example, a cataract should be removed if it prevents
examination or treatment of another eye problem, such as age-related macular
degeneration or diabetic retinopathy. If your eye care professional finds
a cataract, you may not need cataract surgery for several years. In fact,
you might never need cataract surgery. By having your vision tested regularly,
you and your eye care professional can discuss if and when you might need
If you choose surgery, your eye care professional may refer you to a specialist
to remove the cataract.
If you have cataracts in both eyes that require surgery, the surgery will
be performed on each eye at separate times, usually four to eight weeks
Many people who need cataract surgery also have other eye conditions, such
as age-related macular degeneration or glaucoma. If you have other eye conditions
in addition to cataract, talk with your doctor. Learn about the risks, benefits,
alternatives, and expected results of cataract surgery.
There are two types of cataract surgery. Your doctor can explain the differences
and help determine which is better for you:
As with any surgery, cataract surgery poses risks, such as infection and
bleeding. Before cataract surgery, your doctor may ask you to temporarily
stop taking certain medications that increase the risk of bleeding during
surgery. After surgery, you must keep your eye clean, wash your hands before
touching your eye, and use the prescribed medications to help minimize the
risk of infection. Serious infection can result in loss of vision.
- Phacoemulsification, or phaco. A small incision is made on
the side of the cornea, the clear, dome-shaped surface that covers the
front of the eye. Your doctor inserts a tiny probe into the eye. This
device emits ultrasound waves that soften and break up the lens so that
it can be removed by suction. Most cataract surgery today is done by
phacoemulsification, also called "small incision cataract surgery."
- Extracapsular surgery. Your doctor makes a longer incision
on the side of the cornea and removes the cloudy core of the lens in
one piece. The rest of the lens is removed by suction.
After the natural lens has been removed, it often is replaced by an
artificial lens, called an intraocular lens (IOL). An IOL is a clear,
plastic lens that requires no care and becomes a permanent part of your
eye. Light is focused clearly by the IOL onto the retina, improving
your vision. You will not feel or see the new lens.
Some people cannot have an IOL. They may have another eye disease or
have problems during surgery. For these patients, a soft contact lens,
or glasses that provide high magnification, may be suggested.
Cataract surgery slightly increases your risk of retinal detachment. Other
eye disorders, such as high myopia (nearsightedness), can further increase
your risk of retinal detachment after cataract surgery. One sign of a retinal
detachment is a sudden increase in flashes or floaters. Floaters are little
"cobwebs" or specks that seem to float about in your field of vision. If
you notice a sudden increase in floaters or flashes, see an eye care professional
immediately. A retinal detachment is a medical emergency. If necessary,
go to an emergency service or hospital. Your eye must be examined by an
eye surgeon as soon as possible. A retinal detachment causes no pain. Early
treatment for retinal detachment often can prevent permanent loss of vision.
The sooner you get treatment, the more likely you will regain good vision.
Even if you are treated promptly, some vision may be lost.
Source: National Eye
Institute, U.S. National Institutes of Health