Nearsightedness, which is also called myopia (my-O-pee-ah), is an eye condition that causes objects that are not close to a person to appear out of focus or blurry.
Kate noticed she was squinting when she needed to see the blackboard from the back of her classroom. Squinting helped bring the words into focus. It seemed odd to her because she did not remember having to squint when she was younger. But now that she was in middle school, Kate was having trouble seeing things clearly unless they were close.
Kate has a common eye condition known as nearsightedness. Nearsightedness also is called myopia, which comes from a Greek word for “closed eyes”; perhaps because squinting is common in nearsightedness. About 30 percent of Americans have this condition. According to the National Eye Institute, about 80 percent of Americans with nearsightedness are white, 8 percent Hispanic, 7 percent African American, and 5 percent other races or ethnicities. More females (54%) have the condition than males (46%). Often the condition is not noticed until a child is between 8 and 12 years of age. Fortunately, nearsightedness is usually corrected easily with eyeglasses or contact lenses. Surgical correction is also possible.
A person who is nearsighted can see objects that are close but has trouble seeing distant objects clearly. The condition results when a person's eyeball is not shaped to focus properly when light passes through it. In most cases the eyeball is too long, but in some cases the cornea, the clear covering of the eye, is curved too much.
The image passes through the front of the eyeball, as light does through the lens of a camera. As it does, the image is bent in order to focus it. The bending is known as refraction (re-FRAK-shun), and this process focuses the image on the retina at the rear inside of the eyeball. The retina functions like the film in a camera, as it receives the image. If a person's eyeball is not shaped properly, the light from the image is focused in front of the retina, which results in a blurred image for distant objects. Nearsightedness cannot be prevented. It appears to have an inherited component and commonly runs in families.
The first sign that a person is nearsighted usually occurs in childhood between the ages of 8 and 12. Often a teacher notices that a student is having trouble seeing the blackboard. The teacher may notice the student squinting, which can help focus distant objects for nearsighted people. Sometimes the condition is discovered during a routine eye examination during childhood.
As a child passes through the teenage years, nearsightedness often gets worse because as the body grows, the shape of the eyeball changes too. Thus, people with nearsightedness may need to change prescription eyeglasses or contact lenses as they get older. By the time people reach their twenties, however, nearsightedness usually stabilizes and does not get worse.
Some people with mild or moderate nearsightedness may benefit from refractive surgery. A surgeon makes small incisions in the surface of the eye, known as the cornea, to flatten it. Doing so allows the image to be focused on the retina. Another type of surgery involves a laser that changes the shape of the cornea to achieve the same result. Many people who have the surgery no longer need glasses. Surgery often must be postponed until a person has stopped growing and his or her nearsightedness has stabilized.
See Also Astigmatism • Eye Disorders: Overview • Farsightedness
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