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Cataract |
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| A cataract is a cloudy area in the eye's lens that can cause vision problems. | ||
Normal vs. Cloudy Lens
The most common type is related to aging. More than half of all Americans age 65 and older have a cataract.
In the early stages, stronger lighting may lessen the vision problems caused by cataracts. At a certain point, however, surgery may be needed to improve vision. Today, cataract surgery is safe and very effective.
What are the different types of cataract? |
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What is the lens? The lens is the part of the eye that helps focus light onto the retina. The retina is the eye's light-sensitive layer that sends visual signals to the brain. |
The lens is located just behind the iris, the colored part of the eye. In focusing, the lens changes shape. It becomes rounder when you look at nearby objects and flatter for distant objects.
The lens is made mostly of water and protein. The protein is arranged to let light pass through and focus on the retina. Sometimes some of the protein clumps together and starts to cloud a small area of the lens.
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This is a cataract. Over time, the cataract may grow larger and cloud more of the lens, making it hard to see. |
Scientists do know that a cataract won't spread from one eye to the other, although many people develop cataracts in both eyes.
The most common symptoms of a cataract are:
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Problems with light, such as headlights that seem too bright at night, glare from lamps or the sun, or a halo or haze around lights. |
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Double or multiple vision (this symptom goes away as the cataract grows). |
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Frequent changes in your eyeglasses or contact lenses. |
These symptoms can also be a sign of other eye problems. If you have any of these symptoms, check with your eye care professional.
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Normal vision |
The same scene as it might |
| Back to the Top What are the different types of cataract? |
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Age-related cataract: Most cataracts are related to aging. |
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Congenital cataract: Some babies are born with cataracts or develop them in childhood, often in both eyes. These cataracts may not affect vision. If they do, they may need to be removed. |
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Secondary cataract: Cataracts are more likely to develop in people who have certain other health problems, such as diabetes. Also, cataracts are sometimes linked to steroid use. |
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Traumatic cataract: Cataracts can develop soon after an eye injury, or years later. |
How is a cataract detected?
To detect a cataract, an eye care professional examines the lens. A comprehensive eye examination usually includes:
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Visual acuity test: This eye chart test measures how well you see at various distances. |
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Pupil dilation: The pupil is widened with eyedrops to allow your eye care professional to see more of the retina and look for other eye problems. |
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Tonometry: This is a standard test to measure fluid pressure inside the eye. Increased pressure may be a sign of glaucoma. |
Your eye care professional may also do other tests to learn more about the structure and health of your eye.
For an early cataract, different eyeglasses, magnifying lenses, or stronger lighting may improve vision. If these measures don't help, surgery is the only effective treatment. The surgeon removes the cloudy lens and replaces it with a substitute lens.
A cataract needs to be removed only if it affects your vision so much that it interferes with your daily activities. You make that decision. If you decide on surgery, your eye care professional may refer you to another specialist to remove the cataract. If you have cataracts in both eyes, the surgeon will not remove them both at the same time. You will need to have each done separately.
Sometimes, a cataract should be removed even if it doesn't bother you. For example, if it prevents examination or treatment of another eye problem such as age-related macular degeneration or diabetic retinopathy, a cataract should be treated.
Cataract Surgery |
If you've chosen to have surgery, it's helpful to know more about it. This section describes the types of cataract surgery, lens substitutes, and what you can expect before and after surgery.
Is cataract surgery effective?
Cataract removal is one of the most common operations performed in the U.S. today. It is also one of the safest and most effective. More than 90 percent of people who have cataract surgery have better vision afterward. However, even with the best results, your vision may not be as good as before the cataract.
The lens is enclosed in a capsule, an outer covering that holds it in place. There are many different techniques for cataract surgery, but all fall into one of two basic categories:
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Extracapsular surgery: Your doctor opens the front of the capsule and removes the lens, leaving the back of the capsule in place. Sound waves (ultrasound) may be used to soften and break up the cloudy lens so that it can be removed through a narrow hollow tube. This is called phacoemulsification or phaco. |
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Intracapsular surgery: The entire lens is removed, including the capsule. Although extracapsular surgery has largely replaced this technique in the United States, it is safe and effective and may be used in some cases, for example, if the lens is too hard for phaco. |
Currently, lasers cannot be used to remove a cataract. Although scientists are working on ways to use lasers in cataract surgery, these techniques are still being studied.
What are the choices for a lens substitute?
The lens is important for focusing. When it's removed, it usually needs to be replaced. There are three types of substitute lenses: an intraocular lens (IOL), a contact lens, or cataract glasses. Today, about 90 percent of patients choose an IOL. Of them, about 90 percent achieve 20/40 vision or better.
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Intraocular lens An IOL is a clear, plastic lens that is placed in your eye during cataract surgery. It requires no care. With an IOL, you'll have better vision and won't feel or see the new lens. A few people cannot have an IOL because they're sensitive to the material the lens is made of, their eye structure isn't suitable, or they have certain other eye diseases. |
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Contact lens Most people who do not have an IOL wear soft contact lenses. Extended-wear lenses are helpful if you have trouble putting in and taking out contacts. (Your eye care professional can remove and clean the lenses for you periodically.) With all contact lenses, it's important for you to follow instructions about proper use and care. |
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Cataract glasses Some people don't want to use contact lenses or their eyes are too sensitive to wear them. For these people, cataract glasses may be the best choice. Cataract glasses affect vision differently than regular eyeglasses. Their powerful magnification (20-35 percent) may make it harder for you to judge distance and may distort your side vision. Until you've adjusted to these changes, you will need to be careful when you drive or do other activities. |
What happens before surgery?
Before surgery, your eye care professional will do some tests. These may include tests to measure the curve of the cornea (the clear, dome-like structure that protects the front of the eye) and the shape of the eye. For patients who will receive an IOL, this information helps the eye care professional choose the right type of IOL. Other tests may help to determine the health of the retina and to guide the surgery. Photographs of your eye may also be taken before or after surgery.
Many people choose to stay awake during surgery, while others may need to be put to sleep for a short time. If you are awake, you'll have drugs to relax you and to numb the nerves and keep the eye from moving.
What happens after surgery?
Most people who have cataract surgery can go home the same day. Others may have some minor problems, such as bleeding, and may need to stay in the hospital overnight or for a few days.
It's normal to feel itching, sticky eyelids, and mild discomfort for a while after cataract surgery. Some fluid discharge is also common. In most cases, healing will take about 6 weeks.
If you have discomfort, your eye care professional may suggest a non-aspirin pain reliever every 4-6 hours (aspirin can cause bleeding). After 1-2 days, even moderate discomfort should disappear.
After surgery, your eye care professional will schedule exams to check on your progress. You may need to use eyedrops to help healing or to prevent infection or inflammation. For a few days after surgery, you may also take eyedrops or pills to control the pressure inside your eye. Ask your doctor how to use them, when to take them, and what effects they can have.
Problems after surgery are rare, but they can occur. These can include infection, bleeding, higher pressure inside the eye, inflammation (pain, redness, swelling), and detachment of the retina. With prompt medical attention, these problems can be treated.
Certain symptoms could mean that you need prompt treatment. If you have any of the following symptoms, call your eye care professional immediately: unusual pain, loss of vision, or flashing lights.
When will my vision be normal again?
After the surgery, you can read and watch TV almost right away, but your vision may be blurry. The healing eye needs time to adjust so that it can focus properly with the other eye-especially if the other eye has a cataract. This healing period may take many weeks. Your eye care professional can suggest ways to improve your vision during this time.
How long it will be before you can see normally depends on the vision in your other eye, the lens substitute you choose, and your vision before surgery. With an IOL, for example, you may notice that colors have a blue tinge, and that after you've been in bright sunlight, everything is reddish for a few hours. It doesn't take long to adjust to these changes.
Sometimes people who have extracapsular surgery develop an after-cataract. When this happens, the back part of the lens capsule left in the eye becomes cloudy and keeps light from reaching the retina. Unlike a cataract, an after-cataract is treated with a laser. In a technique called YAG capsulotomy, your doctor uses a laser beam to make a tiny hole in the capsule to let light pass through. This is a painless outpatient procedure.
What research is being done?
The NEI is conducting and supporting a number of studies, such as the Age-Related Eye Disease Study (AREDS). In this nationwide clinical study, scientists are examining how cataracts develop and what factors put people at risk for developing them. Also, they are looking at whether certain vitamins and minerals affect cataract development.
Other research is focusing on new ways to prevent, diagnose, and treat cataracts. In addition, scientists are studying the role of genetics in the development of cataracts.
What can you do to protect your vision?
Although we don't know how to protect against cataracts, people over the age of 60 are at risk for many vision problems. If you are age 60 or older, you should have an eye examination through dilated pupils. This kind of exam allows your eye care professional to check for signs of age-related macular degeneration, glaucoma, cataracts, and other vision disorders.
National Eye Institute
National Institutes of Health
NIH Publication No. 96-201
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