A cataract is an opaque, discolored, or cloudy area within the lens of the eye. The lens is composed of water and protein fibers and is normally clear. The clouding of vision associated with cataracts is caused by clumping of the protein fibers in the lens.
A cataract is really a clouding or discoloration in the clear lens of the eye that affects vision. Cataracts may develop in one or both eyes but can't spread from one to the other. There are 3 fundamental kinds of cataracts caused by aging, which are also known as senile cataracts. They're classified by their location in the eye.
Cataracts are widespread among older adults in the general population in the United States, even though some children are born with cataracts and other people develop cataracts in late childhood. About half of people eighty years and older have cataracts or have had surgery to remove cataracts. According to the National Eye Institute, between 300,000 and 400,000 cataracts severe enough to impair vision are diagnosed each year in the United States, and 1.5 million cataract surgeries are performed.
Around the world, cataracts because of aging are the single most essential cause of vision loss; one-third of instances of blindness in Africa are caused by cataracts. As far as is recognized, race is not a factor in the development of cataracts. With regard to sex, various studies have yielded different outcomes as to whether cataracts are more typical in women or men.
Even though researchers do not totally understand why the protein fibers in the lens clump together to form cataracts, they've identified several risk factors for cataract development:
Cataracts are generally diagnosed by a complete eye examination. After the examiner takes a history of the patient's symptoms (including a family history of cataracts and other eye problems), the patient is usually asked to read the letters on an eye chart known as a Snellen chart to test visual acuity, or sharpness of vision. The patient's eye is then dilated with a medication that keeps the pupil wide open, allowing the physician to see the retina and the optic nerve to make certain that they are not damaged or abnormal.
While the eye is dilated, the physician uses a device known as a slit lamp to examine the various parts of the eye in detail by focusing a beam of light into a very small line or slit, which allows the doctor to determine the size and location of a cataract and to exclude glaucoma or other causes of the patient's symptoms. The physician will also usually test the pressure of the fluid inside the eye with a device called a tonometer, which also ensures that the patient doesn't have glaucoma.
Some cataracts are little enough or growing slowly enough that they might not require treatment, particularly if they are not affecting a person's quality of life. In other instances a change in eyeglass or contact lens prescription may be all that is needed. If the cataract is big or opaque sufficient to interfere with the patient's vision, surgical removal is the only efficient treatment. There are no medications that can dissolve or clear up cataracts.
The two basic types of cataract removal are called small incision cataract surgery and extracapsular surgery. In little incision surgery, the ophthalmologist makes a small incision along the side of the cornea and inserts a device that uses ultrasound waves to break up the clouded lens, which is then removed by suction. This technique is also known as phacoemulsification or merely phaco; it could be completed in as little as thirty minutes. In extracapsular surgery, used primarily to treat cataracts that are too dense to be broken up by phacoemulsification, the ophthalmologist makes a longer incision in the cornea and removes the lens all in one piece.
In most instances, the ophthalmologist inserts a new artificial lens, called an intraocular lens (IOL), inside the lens capsule after the cataract is removed. Some patients cannot use an IOL because they've another kind of eye disorder. They're given a new eyeglass prescription or soft contact lenses. Cataract removal could be done in an outpatient center for eye surgery or a hospital.
Most people don't need to stay overnight, but patients should ask a friend or family member to drive them house and help with home care after outpatient surgery. They will need to make use of eye drops to decrease inflammation and also the risk of infection for a couple of days, and they will not be allowed to bend too far forward or lift heavy objects for several days while the eye heals.
Cataract surgery is effective in improving the patient's vision in 90-95 percent of cases. The chief risks are infection, persistent inflammation, changes in the fluid pressure inside the eye, and an increased risk of retinal detachment a condition in which the retina separates from the tissues at the back of the eye. In a few instances the patient's IOL will need to be removed or replaced. Serious complications occur in fewer than one per 1,000 cataract surgeries.
Cataracts can't always be totally prevented, but their development can be slowed by a combination of lifestyle changes and good eye care:
Current research on cataracts includes the possibility of developing medications to treat cataracts. Other research being conducted by the National Eye Institute concerns genetic studies that might help doctors understand how cataracts develop and studies of the effects of sunlight exposure on the lens of the eye.
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