Cataracts
Cataracts are the leading cause of blindness worldwide. Approximately 20.5 million Americans age 40 and older have cataracts. More than half of all Americans develop cataracts by age 80.
A cataract is a clouding of the normally clear lens of the eye. Persons with cataracts often say they feel as if they are looking through a window that is frosted or yellowed. When the lens becomes cloudy, light rays cannot pass through it easily and vision becomes blurry. A cataract does not form on the eye, but rather within the eye.
Cataracts start out small and have little effect on vision at first. But as the cataract grows and becomes denser, so does the effect on vision.
There are many misconceptions about cataracts. Cataracts are not:
- A film over the eye
- Caused by overusing the eyes
- Spread from one eye to the other
- A cause of irreversible blindness
Symptoms of Cataracts
Common symptoms of cataracts include:
- A painless blurring of vision
- Light sensitivity
- Poor night vision
- Double vision in one eye
- The need for brighter light to read
- Fading or yellowing of colors
The amount and pattern of cloudiness within the lens varies. If the cataract is not near the center of the lens, the person with the cataract may not even be aware that the cataract is present.
The most common type of cataract is related to aging of the eye. Persons prone to developing cataracts usually have one or more of the following contributing factors:
- Family history
- Other medical problems, such as diabetes
- Injury to the eye
- Medications, especially steroids
- Long-term, unprotected exposure to sunlight
- Previous eye surgery
In some cases, however, cataracts appear in patients with none of the contributing factors listed.
Researchers are gradually identifying factors that may cause cataracts along with information that may help to prevent them.
Many studies suggest that exposure to ultraviolet (UV) light is associated with cataract development, so eye care practitioners recommend wearing sunglasses and a wide-brimmed hat to lessen exposure to UV rays.
Some eye care practitioners believe that a diet high in antioxidants, such as beta-carotene (vitamin A), selenium and vitamins C and E, may forestall cataract development. Others believe that eating too much salt may increase the risk of developing cataracts.
Other risk factors may include cigarette smoking, air pollution and heavy alcohol consumption.
A thorough eye examination by an ophthalmologist (a medical doctor specializing in diseases of the eye) can detect the presence of a cataract, as well as any other conditions that may be causing blurred vision or other eye problems. A regular vision examination with an optometrist (a health care professional specializing in vision correction) may detect the possibility of a cataract, but an ophthalmologist must confirm the diagnosis.
The time it takes for a cataract to develop varies among individuals, and may even be different between the two eyes of an individual. Most age-related cataracts progress gradually over a period of years.
Other cataracts, especially in younger people and people with diabetes, may progress rapidly over a short time. It is not possible to predict exactly how fast cataracts will develop in any given person.
Surgery is the only way a cataract can be removed. However, if the cataract is not severely limiting visual acuity, surgery may not be needed. Sometimes a simple change in eyeglass prescription will help the patient to see better. However, since cataracts tend to progress, the cataract may eventually need to be removed surgically. Surgery should be considered when cataracts cause enough loss of vision to interfere with daily activities.
Sunglasses that screen out ultraviolet (UV) light rays or regular eyeglasses with a clear, anti-UV coating offer protection from excessive sunlight that may help slow the progression of cataracts.
However, there are no medications, dietary supplements or exercises that have been shown to prevent or cure cataracts.
Problems with other parts of the eye, such as the cornea, retina or optic nerve, can be responsible for vision loss and may prevent a patient from achieving much or any improvement in vision after cataract surgery. Only an ophthalmologist can judge the degree of visual improvement that is likely following cataract surgery. If improved vision is unlikely, cataract removal may not be recommended.
Over 1.4 million people have cataract surgery each year in the United States, and more than 95% of those surgeries are performed with no complications.
During cataract surgery, which is usually performed under local or topical anesthesia as an outpatient procedure, the cloudy lens is removed from the eye. In most cases, the focusing power of the natural lens is restored by replacing it with a permanent intraocular lens implant.
Following cataract surgery, the natural capsule that supports the intraocular lens may become cloudy. Laser surgery is then used to open this cloudy capsule, restoring clear vision.
Cataract surgery is a highly successful procedure. It is important to understand that complications, though rare, can occur during or after the surgery, some severe enough to limit vision.
The National Eye Institute of the National Institutes of Health is an excellent source for more information about cataracts.
