Cataracts

A cataract is a clouding of the eye's lens that can cause vision problems. 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 and eyeglasses may lessen 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 is the lens?

The lens is the part of the eye that helps focus light on the retina. The retina is the eye's light-sensitive layer that sends visual signals to the brain. In a normal eye, light passes through the lens and gets focused on the retina. To help produce a sharp image, the lens must remain clear.

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. This can start to cloud small areas of the lens, blocking some light from reaching the retina and interfering with vision. This is a cataract.

In its early stages, a cataract may not cause a problem. The cloudiness may affect only a small part of the lens. However, over time, the cataract may grow larger and cloud more of the lens, making it harder to see. Because less light reaches the retina, your vision may become dull and blurry. A cataract won't spread from one eye to the other, although many people develop cataracts in both eyes.

Although researchers are learning more about cataracts, no one knows for sure what causes them. Scientists think there may be several causes, including smoking, diabetes, and excessive exposure to sunlight.

The most common symptoms of a cataract are:

• Cloudy or blurry vision.
• Problems with light. These can include headlights that seem too bright at night; glare from lamps or very bright sunlight; or a halo around lights.
• Colors that seem faded.
• Poor night vision.
• Double or multiple vision (this symptom often goes away as the cataract grows).
• Frequent changes in your eyeglasses or contact lenses.

When a cataract is small, you may not notice any changes in your vision. Cataracts tend to grow slowly, so vision gets worse gradually. Some people with a cataract find that their close-up vision suddenly improves, but this is temporary. Vision is likely to get worse again as the cataract grows.

• Age-related cataract: Most cataracts are related to aging.
• 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.
• 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.
• 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:

• Visual acuity test: This eye chart test measures how well you see at various distances.
• Pupil dilation: The pupil is widened with eyedrops to allow your eye care professional to see more of the lens and retina and look for other eye problems.
• Tonometry: This is a standard test to measure fluid pressure inside the eye. Increased pressure may be a sign of glaucoma.

  For an early cataract, vision may improve by using different eyeglasses, magnifying lenses, or stronger lighting. If these measures don't help, surgery is the only effective treatment. This treatment involves removing the cloudy lens and replacing it with a substitute 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 that decision together. In most cases, waiting until you are ready to have cataract surgery will not harm your eye. If you decide on surgery, your eye care professional may refer you to a specialist to remove the cataract. If you have cataracts in both eyes, the doctor 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 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.

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. In about 90 percent of cases, people who have cataract surgery have better vision afterward.

How is a cataract removed?

There are two primary ways to remove a cataract. Your doctor can explain the differences and help determine which is best for you:

• Phacoemulsification, or phaco. Your doctor makes a small incision on the side of the cornea, the clear, dome-shaped surface that covers the front of the eye. The doctor then inserts a tiny probe into the eye. This device emits ultrasound waves that soften and break up the cloudy center of the lens so it can be removed by suction. Most cataract surgery today is done by phaco, which is also called small incision cataract surgery.

• Extracapsular surgery. Your doctor makes a slightly longer incision on the side of the cornea and removes the hard center of the lens. The remainder of the lens is then removed by suction.

Some people cannot have an IOL. They may have problems during surgery, or maybe they have another eye disease. For these people, a soft contact lens may be suggested. For others, glasses that provide powerful magnification may be better.