Nearsightedness



Nearsightedness is an eye disorder that causes objects that are not close to a person to appear out of focus or blurry.

KEYWORDS

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Myopia

Ophthalmology

Optometry

Vision

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 started to have trouble seeing things unless they were close.

Kate has a common eye condition known as nearsightedness. It affects more than 60 million people in the United States, and often is not noticed until a child is between 8 and 12 years old. Fortunately, near-sightedness is usually corrected easily with eyeglasses or contact lenses.

What Is Nearsightedness?

Nearsightedness means a person can see things 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 front of the eye is curved abnormally.

The front of the eyeball, like the lens of a camera, is where the image passes. As it does, the image is bent in order to focus it. The bending is known as refraction (re-FRAK-shun), and it focuses the image on the

Normal vs. nearsighted focus.
Normal vs. nearsighted focus.
retina at the rear inside of the eyeball. The retina is something like the film in a camera. 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. This results in a blurred image for distant objects.

How Is Nearsightedness Diagnosed?

The first sign that a person is nearsighted usually occurs in childhood between the ages of 8 and 12. It is often a teacher who 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. Nearsightedness also is called "myopia," which comes from a Greek word for "closed eyes," perhaps because squinting is common in nearsightedness.

What Are the Treatment Options for Nearsightedness?

Eyeglasses

Prescription (pre-SKRIP-shun) eyeglasses are the most common solution for nearsightedness. The glasses change how the light passing through the eye is focused. Contact lenses worn on the eyeball also can help nearsightedness.

As a child passes through the teenage years, nearsightedness often gets worse. This is 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.

Surgery

Some people with mild or moderate nearsightedness may benefit from refractive surgery. A surgeon cuts small incisions in the surface of the eye, known as the cornea, to flatten it. This 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 at all.

See also
Astigmatism
Farsightedness

Resources

Book

Cassel, Gary H., M.D., Michael D. Billig, O.D., and Harry G. Randall, M.D. The Eye Book: A Complete Guide to Eye Disorders and Health. Baltimore: Johns Hopkins University Press, 1998. A good general reference on eye problems.

Organization

The U.S. National Eye Institute posts a resource list of eye health-related publications and organizations at its website.
http://www.nei.nih.gov/publications/sel-org.htm

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