What is nearsightedness?

Nearsightedness, also called myopia, is a condition in which your eyes can see clearly objects that are close but not objects that are far away.

How does it occur?

Nearsightedness occurs when light from a distant object does not focus properly in the eyeball. Normally, as light enters the cornea (the clear covering of the eye) and then the lens inside the eye, the light is refracted (bent). The refracted light then lands on the retina (the back inside of the eyeball). The image from the retina then travels along the optic nerve to the brain. If the eyeball grows to be too long, light from distant objects no longer focuses on the retina, and the retina receives a fuzzy image rather than a clear one.

Nearsightedness is hereditary, which means you inherit the tendency to be nearsighted from your father or mother. Nearsightedness usually develops when you are 8 to 12 years of age. The eyeball grows as the rest of the body grows, but nearsightedness occurs if your eyeball grows to be more oval than round.

Reading too much, using your eyes in dim light, and poor nutrition do not cause nearsightedness.

What are the symptoms?

The major symptoms of nearsightedness are blurred vision, eye discomfort, or eye strain. Usually, these symptoms can be completely corrected with glasses, contact lenses, or surgery.

How is it diagnosed?

Your doctor will be either an ophthalmologist or an optometrist. An ophthalmologist is a medical doctor who is trained in diagnosing and treating eye problems. He or she prescribes eyeglasses, treats injuries to eye, and performs surgery. An optometrist is a person trained in diagnosing refraction errors and prescribing corrective lenses.

To diagnose nearsightedness:

• Your doctor will ask you to read letters or numbers on a chart 20 feet away. This test measures your ability to see the details of distant objects to determine if you need glasses and, if so, what kind.

• Your doctor will shine a narrow beam of light into your eye and then observes the light that is reflected back from the retina. Moving the light and watching your eye helps the doctor determine how the nearsightedness can be corrected.

  Your doctor may give you eyedrops before this test so that it is easier to see into your eyes. These drops may blur your vision, make your eyes sensitive in bright light, or rarely cause a skin rash, fast pulse, or fever. All of these effects are temporary.

• Your doctor will ask you which of several different lenses like those in glasses make your distance vision the clearest.

How is it treated?

Until recently, nearsightedness was almost always corrected with eyeglasses or contact lenses. However, now surgery can also correct nearsightedness.

Corrective lenses:

Corrective lenses (regular eyeglasses, bifocals, trifocals, and contact lenses) can correct nearsightedness by helping the eyeball to focus light rays properly on the retina.

Generally, you will choose between glasses and contacts, with some advice from your doctor. Both have advantages and disadvantages. Many people choose contact lenses because they think they look better without glasses. In addition, contacts may make your side vision better, especially if you need thick glasses.

You can usually wear contacts if you are willing to get used to them. You may have difficulties if you have trouble putting something in your eyes, have very dry eyes, or have allergies that would make your contacts uncomfortable. However, there are very few eye problems that would keep you from wearing contacts if you want to.

Surgery:

The most common surgical procedure to correct nearsightedness is radial keratotomy. In this procedure, the doctor makes several incisions (cuts) in a spoke-like pattern around the cornea to flatten it. The light rays from distant objects then focus properly on the retina. This procedure permanently corrects nearsightedness if the surgery is successful.

How can I take care of myself?

Prevent eyestrain by using bright light for reading or doing close work and by wearing your glasses as prescribed.

Have your eyes checked regularly to see if other problems develop or if you need stronger glasses or contacts.

How can nearsightedness be prevented?

Because the tendency to be nearsighted is inherited, there is nothing you can do to prevent it. However, holding near work or reading materials as far away as possible and removing glasses for near work may slow down the worsening of myopia.