Cataracts

A cataract is a clouding of the eye's lens (Read about "The Eye"), most often caused by age. The lens lies behind the pupil of the eye and is normally clear. With a cataract, a cloudy or opaque area develops. According to the National Eye Institute (NEI), this can start happening in a person's 40's or 50's, although cataracts usually don't start to interfere with vision until later in life. NEI says most cataracts are age-related, but cataracts can also develop for other reasons, including trauma or diseases such as diabetes. Cataracts can also occur in infants and children; they are one of the causes of amblyopia or lazy eye in children. (Read about "Amblyopia")

Cataracts start out small, which is why they may not produce any vision changes at first. As cataracts grow, however, so do the symptoms. These include:

• blurred vision
• glare from lights
• sensitivity to lights
• dulling of colors
• progressive difficulty reading and seeing

According to NEI although most cataracts are related to aging, there are other types of cataracts:

• Secondary cataract - Cataracts can form after surgery for other eye problems, such as glaucoma. (Read about "Glaucoma") Cataracts also can develop in people who have other health problems, such as diabetes. (Read about "Diabetes") Cataracts are sometimes linked to steroid use.
• Traumatic cataract - Cataracts can develop after an eye injury, sometimes years later. (Read about "Eye Injury")
• 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 form

The lens of the eye lies behind the iris and the pupil. It focuses light onto the retina (which is at the back of the eye), where an image is recorded. The lens also adjusts the eye's focus, letting us see things clearly at varying distances.

The lens is made of mostly water and protein. Normally, the protein is arranged in an orderly way that keeps the lens clear and allows light pass through it. But as we get older, some of the protein may clump together and start to cloud a small area of the lens. This is a cataract. Over time, the clumping can get bigger and affect more of the lens, making it harder to see. NEI Researchers suspect that there are several potential causes of cataract, including smoking and diabetes. Research looking into other links, such as excess sun exposure, continues.

Precautions and treatment

Meanwhile, there are precautions you can take. Routine eye exams can spot cataracts early. (Read about "Eye Exams") Your doctor can then advise you about treatment. If the cataract isn't interfering with vision, no treatment may be needed. If you are having problems, surgery to remove the cataract may be necessary.

According to the American Academy of Ophthalmology, over 95 percent of cataract surgeries improve vision, although it's important for anyone who's had cataract surgery to be aware of and report any complications after the procedure. Cataract surgery is one of the most common surgeries in this country, with over a million and a half cataract procedures performed each year, according to the National Institutes of Health. During surgery, the clouded lens is usually replaced with a clear synthetic lens. There are different types of intraocular lens (IOL) styles available. These include monofocal (which focus best on long distances), toric (which can correct astigmatism), and multifocal (which can focus at different distances). There are advantages and disadvantages to each type, so you should discuss in advance what's best for you with your doctor. Surgery is most often done on an outpatient basis, with the patient fully awake. Local anesthetic drops are applied to the eye's surface and patients often receive a mild sedative as well.

A number of studies are under way to determine why cataracts form and possible ways to prevent them. Although the exact cause of cataracts isn't known, studies show that people who spend a lot of time in the sun may develop cataracts earlier that others. As a result, many doctors recommend using good sunglasses to block out UV light from the sun. (Read about "Eyes and Sun") Diabetics may have a higher risk of developing cataracts, too, and should talk with their doctors about their risk. The American Optometric Association also says that certain medications and smoking are risk factors. (Read about "Quit Smoking")

It's also important for everyone to ask their doctor how often they should schedule eye exams. Regular screening is the best way to find potential problems early.

Related Information:

    Refractive Errors

    Retinitis Pigmentosa

    Glossary of Vision Terms