Cataracts
What is it?
A cataract is a cloudiness, called opacity, in the eye's lens. The cataract causes a progressive, but painless loss of
vision.
Who gets it?
Cataracts are very common in the elderly. People between the ages of 52 and 64 have a 50% chance of having a cataract. This risk increases to 70% for people over the age of 70. Cataracts in people under the age of 50 are unusual. Cases of cataracts in younger people can include congenital cataracts in newborns, traumatic cataracts, and cataracts as a result of diabetes or other eye
diseases.
What causes it?
The lens of the eye is behind the iris, which is the colored part of the eye. The lens changes its shape to focus light onto the retina. About 35% of the lens is made up of protein and the remaining 65% is water. As people age, the lens' proteins can naturally deteriorate, which can cause cataracts. Congenital cataracts in newborns are caused by genetic defects or an infection or disease in the mother during pregnancy. Traumatic cataracts are caused by a foreign body entering or trauma to the lens or eye. People with illnesses such as diabetes and eye diseases can have cataracts as complications, which is why these types are called complicated cataracts. Cataracts can also be caused from exposure to chemicals, such as steroids, and from exposure to the sun's ultraviolet (UV) rays. Lifestyle factors, such as smoking, alcohol consumption, and a diet high in saturated fats may also contribute to the formation of
cataracts.
What are the symptoms?
All light entering the eye must pass through the lens, so any change in the lens can block or distort the light and affect vision. The most common symptoms of cataracts are a gradual blurring of the vision; poor central vision; increased sensitivity to light, including seeing halos, glare, and scattered light; changes in color vision; and the need to frequently change eyeglass prescriptions. As the cataract progresses, the pupil begins to take on a milky-white appearance. The cataract is considered "ripe" or mature when the lens is completely opaque. Specific symptoms depend upon the location of the cataract. The lens consists of three major parts - the nucleus, the cortex, and the capsule. The nucleus is the central part of the lens, the cortex surrounds the nucleus, and the capsule is the outer layer. A cataract that forms at the back of the lens is called a posterior subcapular cataract. This type of cataract affects vision more than any other type because it occurs at the point where light rays cross. So, it will have a great affect on vision in bright light. Nuclear cataracts, which occur in the central part of the lens, may improve close-up vision at first because they cause the light to be refocused. At first, people who needed reading glasses may find they can read without them, which is known as gaining second sight. Cataracts on the cortex are called cortical cataracts and cause gradually blurring vision. Cataracts that remain small or on the edge of the lens may cause only minor visual
changes.
How is it diagnosed?
Eye care specialists called ophthalmologists and optometrists can detect cataract growth by listening to your symptoms, performing a test of your vision using an eye chart, and by examining the eye itself. The doctor will shine a light, called an ophthalmoscope, into your eye to check for any cloudiness of the lens or color changes. These types of changes can be seen before any symptoms even occur. Using a microscope called a slit lamp, the doctor can see the location of the cataract. The doctor may also perform a glare test, to test your reaction to
light.
What is the treatment?
Your doctor will monitor the cataract's growth during regular checkups. If the cataract doesn't affect your lifestyle or work, treatment may be as simple as changing your eyeglass prescription, using reflected rather than direct lighting when reading, wearing sunglasses in bright light, and taking medication to keep the pupil dilated. If this type of treatment does not help and the cataract is seriously affecting your vision, a surgeon may need to remove the lens using a procedure called cataract extraction surgery. This procedure does not require general anesthesia or a hospital stay. Only one eye at a time is operated on.
First, the surgeon numbs the eye area. He or she may use ultrasonic vibration to break up the lens before removing the pieces with a narrow, hollow suction tube. This procedure is called phacoemulsification. A new plastic or silicone lens may be inserted to replace the lens with the cataract. This is called an intraocular lens implantation. If you do not have an intraocular lens, you will need to wear contact lenses or special cataract glasses. Most people go home the same day as the surgery. You will probably feel some discomfort in the eye and have some temporary distortion of vision. You will need to put eyedrops or ointment in the eye to prevent infection, and wear protective glasses for a few weeks after surgery until the healing is complete.
Cataract extraction surgery has an average 90% success rate in restoring vision. In some cases, patients develop an opacity behind the lens implant after surgery. This type of cloudy membrane usually can be treated with a
laser.
Self-care tips
Because early detection of any illness is extremely important, it's important to have regular eye exams, especially as you get older. Talk to your doctor about more frequent eye exams if you are using any type of steroid medications. You can help lower your risk for developing cataracts by not smoking or abusing alcohol, and by wearing sunglasses to protect your eyes from ultraviolet light. Also follow a diet that is rich in green, leafy vegetables and yellow vegetables, and low in saturated fat. Taking an antioxidant vitamin supplement, especially vitamin A, may help to protect your eyes.
This information has been designed as a comprehensive and quick reference
guide written by our health care reviewers. The health information written
by our authors is intended to be a supplement to the care provided by your
physician. It is not intended nor implied to be a substitute for
professional medical advice.
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