Cataracts

A cataract is a cloudy area in the normally clear lens of the eye. When cataracts form, they cause vision loss. If left untreated, dense cataracts can cause blindness.


Anatomy
The lens of the eye is located behind the iris (the colored part of the eye) and the pupil (the part of the eye that contracts and expands to control the amount of light entering the eye). The lens focuses light rays on the retina in the back of the eye, where an image is projected. The lens also adjusts the focus of the eye by helping you see clearly, both at a distance and close up.



The lens is composed of mostly water and protein. When cataracts form, the protein clumps together. This alters the way light passes through the lens and causes decreased transparency. As a result, less light reaches the retina.


Causes/associated factors
Cataracts can develop in one or both eyes and may progress at different rates. Among older adults, cataracts are responsible for most cases of vision loss. In fact, aging is the most common cause of cataracts. Although cataracts usually develop in people older than age 65, they may develop in adults as young as age 40.
Other causes of cataracts include:

congenital defects (A baby can be born with cataracts in one or both eyes. Cataracts may develop due to genetics, a birth injury, nutritional deficiency while in the womb or certain maternal illnesses, such as rubella.)
radiation exposure
medication side effects, such as from long-term steroid use
chronic medical conditions, such as diabetes
injury to the eye, such as a direct blow or puncture wound
long-term, unprotected exposure to sunlight
secondary eye infections
chronic eye inflammations
previous eye surgery
cigarette smoking

Signs/symptoms
The amount and pattern of cloudiness caused by a cataract within the lens can vary. Other changes can also occur within the lens, depending on the cause of the cataract. Common symptoms include:
in early stages, improvement of near vision
blurred vision
problems with glare
frequent vision prescription changes
double vision
poor night vision
fading of colors
gradual lens yellowing, which may cause objects to appear more yellow or brown
seeing halos surrounding lights
image distortion, such as straight lines appearing crooked

Diagnosis
Cataracts are diagnosed with an eye exam. Before the exam, the doctor may give you eyedrops to dilate your pupils. Equipment such as a slit-lamp biomicroscope may be used to help determine the type, size and location of the cataract. In certain cases, other tests may be needed to determine how severely your vision is impaired, how your eyes handle glare and contrast, or how well you may see after treatment. Discuss these options with your ophthalmologist.

Treatment
If your symptoms are mild, treatment may be as simple as new eyeglasses, bifocals, contact lenses or a magnifying lens. If your vision loss interferes with daily activities or, rarely, if a cataract contributes to other eye diseases or prevents their treatment, surgical removal of the cataract may be recommended. In this case, the cloudy natural lens would be replaced with an artificial plastic lens.
Specific types of cataract surgery include:

Extracapsular surgery: Surgical removal of the hard center of the lens, followed by suction removal of the remaining soft parts of the lens.
Phacoemulsification: Softening the center of the lens with sound waves, followed by suction removal of the lens.

Procedure
Cataract surgery is usually done on an outpatient basis. You may be asked to avoid food and fluids the morning of the procedure. Depending on the type of surgery, your doctor may have other instructions for you to follow as well.
When you arrive for the surgery, your doctor may give you eyedrops to dilate your pupils and medication to help you relax. You may receive a local or general anesthetic. (The local anesthetic will numb the affected area, while general anesthesia will render you temporarily unconscious.)

The doctor will begin by making a small incision in your eye. Using tiny instruments, he or she will remove the cloudy lens. After the artificial lens is placed in your eye, the incision may be closed with fine sutures. (When sutures are used, they rarely need to be removed.) The procedure takes less than an hour. Most people report minimal pain or itching after the procedure.


Postprocedure care
After surgery, the doctor may put a patch or shield over your eye. If everything goes smoothly, you'll be sent home after a short stay (usually two to three hours) in the recovery area. Call a taxi or arrange ahead of time for someone to drive you home.
Normal swelling may cause cloudy vision for a few days or weeks. Your doctor will monitor your progress and tell you how to take care of yourself at home. For example, you'll need to avoid rubbing your eye, straining or lifting heavy objects. The entire healing process usually takes about two weeks. New prescription lenses may be prescribed two weeks after the procedure. Make sure you have your doctor's approval before you begin driving again.

After surgery, call your doctor if you have an eye injury or notice:

pain that's not relieved by recommended medication
vision loss
nausea, vomiting or excessive coughing
other symptoms as described by your doctor
If you have a cataract in both eyes, wait for the first eye to heal before having the second cataract removed.


Benefits
For most people, cataract surgery improves vision and focusing power.

Risks
Complications can occur during or after surgery, including:
infection
bleeding
glaucoma (a condition in which the fluid inside the eye is under abnormally high pressure)
displacement of the artificial lens
problems with the cornea (the outer layer of the eye)
chronic inflammation
retinal detachment (the separation of the retina from the back of the eye)
drooping eyelid
blindness
loss of the eye
About 30 percent of people who have any form of extracapsular surgery experience lens cloudiness about a year or more after surgery. This cloudiness causes the same vision problems as a cataract. If this occurs, the doctor may do a laser procedure called YAG capsulotomy to restore your vision. No anesthesia is required, and no surgical incisions are made.

As always, discuss the risks with your doctor before surgery.


Pregnancy-specific information
Pregnancy doesn't increase the risk of developing cataracts.

Senior-specific information
About 50 percent of 65- to 74-year-olds have cataracts. For adults older than age 75, the rate jumps to 70 percent. Some experts recommend eye exams every one to two years beginning at ages 60 to 65 to detect eye disorders.

Prevention
To help prevent cataracts, wear sunglasses that block ultraviolet rays. During sporting events or other potentially risky activities, prevent eye injuries by wearing safety glasses. If you smoke, quit.