What is Cataract? |
A cataract is a clouding of the usually
clear lens of the eye. For people who have cataracts, seeing through cloudy
lenses is a bit like looking through a frosty or fogged-up window. Clouded
vision caused by cataracts can make it more difficult to read, drive a car
(especially at night) or see the expression on a friend's face.
Most cataracts develop slowly and don't
disturb your eyesight early on. But with time, cataracts will eventually
interfere with your vision.
At first, stronger lighting and eyeglasses can help you deal with cataracts. But if impaired vision interferes with your usual activities, you might need cataract surgery. Fortunately, cataract surgery is generally a safe, effective procedure.
Symptoms of Cataract
Signs and
symptoms of cataracts include:
- Clouded, blurred, or dim vision
- Increasing difficulty with vision at night
- Sensitivity to light and glare
- Need for brighter light for reading and other
activities
- Seeing "halos" around lights
- Frequent changes in eyeglass or contact lens
prescription
- Fading or yellowing of colors
- Double vision in a single eye
At first, the cloudiness in your vision caused by a cataract may affect only a tiny part of the eye's lens and you may be unaware of any vision loss. As the cataract grows more prominent, it clouds more of your lens and distorts the light passing through the lens. This may lead to more noticeable symptoms.
When to see a doctor
Make an
appointment for an eye exam if you notice any changes in your vision. If you
develop sudden vision changes, such as double vision or flashes of light,
sudden eye pain, or sudden headache, see your doctor right away.
What is Cataract? |
Causes of Cataract
Most
cataracts develop when aging or injury changes the tissue that makes up the
eye's lens. Proteins and fibers in the lens begin to break down, causing vision
to become hazy or cloudy.
Some inherited genetic disorders that cause other health problems can increase your risk of cataracts. Cataracts can also be caused by other eye conditions, past eye surgery, or medical conditions such as diabetes. Long-term use of steroid medications, too, can cause cataracts to develop.
How a cataract forms
A cataract is a cloudy lens. The lens is
positioned behind the colored part of your eye (iris). The lens focuses light
that passes into your eye, producing clear, sharp images on the retina — the
light-sensitive membrane in the eye that functions like the film in a camera.
As you age, the lenses in your eyes become
less flexible, less transparent, and thicker. Age-related and other medical
conditions cause proteins and fibers within the lenses to break down and clump
together, clouding the lenses.
As the cataract continues to develop, the
clouding becomes denser. A cataract scatters and blocks the light as it passes
through the lens, preventing a sharply defined image from reaching your retina.
As a result, your vision becomes blurred.
Cataracts generally develop in both eyes, but not always at the same rate. The cataract in one eye may be more advanced than the other, causing a difference in vision between eyes.
Types of cataracts
Cataract types include:
- Cataracts affect the center of the lens
(nuclear cataracts). A nuclear cataract may at first cause more
nearsightedness or even a temporary improvement in your reading vision.
But with time, the lens gradually turns more densely yellow and further
clouds your vision.
As the
cataract slowly progresses, the lens may even turn brown. Advanced yellowing or
browning of the lens can lead to difficulty distinguishing between shades of
color.
- Cataracts that affect the edges of the lens
(cortical cataracts). A cortical cataract begins as whitish,
wedge-shaped opacities or streaks on the outer edge of the lens cortex. As
it slowly progresses, the streaks extend to the center and interfere with
light passing through the center of the lens.
- Cataracts that affect the back of the lens
(posterior subcapsular cataracts). A posterior subcapsular cataract starts as
a small, opaque area that usually forms near the back of the lens, right
in the path of light. A posterior subcapsular cataract often interferes
with your reading vision, reduces your vision in bright light, and causes
glare or halos around lights at night. These types of cataracts tend to
progress faster than other types do.
- Cataracts you're born with (congenital
cataracts). Some
people are born with cataracts or develop them during childhood. These
cataracts may be genetic or associated with an intrauterine infection or
trauma.
These
cataracts may also be due to certain conditions, such as myotonic dystrophy,
galactosemia, neurofibromatosis type 2, or rubella. Congenital cataracts don't
always affect vision, but if they do, they're usually removed soon after
detection.
Risk factors
Factors that increase your risk of
cataracts include:
- Increasing age
- Diabetes
- Excessive exposure to sunlight
- Smoking
- Obesity
- High blood pressure
- Previous eye injury or inflammation
- Previous eye surgery
- Prolonged use of corticosteroid medications
- Drinking excessive amounts of alcohol
Prevention
No studies have proven how to prevent
cataracts or slow the progression of cataracts. But doctors think several
strategies may be helpful, including:
- Have regular eye examinations. Eye
examinations can help detect cataracts and other eye problems at their
earliest stages. Ask your doctor how often you should have an eye
examination.
- Quit smoking. Ask your doctor for suggestions about how
to stop smoking. Medications, counseling, and other strategies are
available to help you.
- Manage other health problems. Follow
your treatment plan if you have diabetes or other medical conditions that
can increase your risk of cataracts.
- Choose a healthy diet that includes plenty of
fruits and vegetables. Adding a variety of colorful fruits and
vegetables to your diet ensures that you're getting many vitamins and
nutrients. Fruits and vegetables have many antioxidants, which help
maintain the health of your eyes.
Studies
haven't proved that antioxidants in pill form can prevent cataracts. But a
large population study recently showed that a healthy diet rich in vitamins and
minerals was associated with a reduced risk of developing cataracts. Fruits and
vegetables have many proven health benefits and are a safe way to increase the
number of minerals and vitamins in your diet.
- Wear sunglasses. Ultraviolet
light from the sun may contribute to the development of cataracts. Wear
sunglasses that block ultraviolet B (UVB) rays when you're outdoors.
- Reduce alcohol use. Excessive
alcohol use can increase the risk of cataracts.
Diagnosis of Cataract
To determine
whether you have a cataract, your doctor will review your medical history and
symptoms, and perform an eye examination. Your doctor may conduct several
tests, including:
- Visual acuity test. A visual
acuity test uses an eye chart to measure how well you can read a series of
letters. Your eyes are tested one at a time, while the other eye is
covered. Using a chart or a viewing device with progressively smaller
letters, your eye doctor determines if you have 20/20 vision or if your
vision shows signs of impairment.
- Slit-lamp examination. A slit
lamp allows your eye doctor to see the structures at the front of your eye
under magnification. The microscope is called a slit lamp because it uses
an intense line of light, a slit, to illuminate your cornea, iris, lens,
and the space between your iris and cornea. The slit allows your doctor to
view these structures in small sections, which makes it easier to detect
any tiny abnormalities.
- Retinal exam. To prepare for a retinal exam, your eye
doctor puts drops in your eyes to open your pupils wide (dilate). This
makes it easier to examine the back of your eyes (retina). Using a slit
lamp or a special device called an ophthalmoscope, your eye doctor can examine
your lens for signs of a cataract.
- Applanation tonometry. This test
measures the fluid pressure in your eye. There are multiple different devices
available to do this.
Treatment of Cataract
When your prescription glasses can't clear
your vision, the only effective treatment for cataracts is surgery.
When to consider cataract surgery
Talk with your eye doctor about whether
surgery is right for you. Most eye doctors suggest considering cataract surgery
when your cataracts begin to affect your quality of life or interfere with your
ability to perform normal daily activities, such as reading or driving at
night.
It's up to you and your doctor to decide
when cataract surgery is right for you. For most people, there is no rush to
remove cataracts because they usually don't harm the eyes. But cataracts can
worsen faster in people with certain conditions, including diabetes, high blood
pressure, or obesity.
Delaying the procedure generally won't
affect how well your vision recovers if you later decide to have cataract
surgery. Take time to consider the benefits and risks of cataract surgery with
your doctor.
If you choose not to undergo cataract
surgery now, your eye doctor may recommend periodic follow-up exams to see if
your cataracts are progressing. How often you'll see your eye doctor depends on
your situation.
What happens during cataract surgery
Cataract surgery involves removing the
clouded lens and replacing it with a clear artificial lens. The artificial
lens, called an intraocular lens, is positioned in the same place as your
natural lens. It remains a permanent part of your eye.
For some people, other eye problems
prohibit the use of an artificial lens. In these situations, once the cataract
is removed, vision may be corrected with eyeglasses or contact lenses.
Cataract surgery is generally done on an
outpatient basis, which means you won't need to stay in a hospital after the
surgery. During cataract surgery, your eye doctor uses a local anesthetic to
numb the area around your eye, but you usually stay awake during the procedure.
Cataract surgery is generally safe, but it
carries a risk of infection and bleeding. Cataract surgery increases the risk
of retinal detachment.
After the procedure, you'll have some
discomfort for a few days. Healing generally occurs within a few weeks.
If you need cataract surgery in both eyes,
your doctor will schedule surgery to remove the cataract in the second eye
after you've healed from the first surgery.
What is Cataract? |
Lifestyle and home remedies
To deal with symptoms of cataracts until
you decide to have surgery, try to:
- Make sure your eyeglasses or contact lenses are
the most accurate prescription possible
- Use a magnifying glass to read if you need
additional help reading
- Improve the lighting in your home with more or
brighter lamps
- When you go outside during the day, wear
sunglasses or a broad-brimmed hat to reduce glare
- Limit your night driving
Self-care measures may help for a while, but as the cataract progresses, your vision may deteriorate further. When vision
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