Nearsightedness (Myopia)

What is nearsightedness?

Nearsightedness means that you see close objects clearly, but distant objects are blurry. This happens when the eyeball is too long or when the outer layer of the eye, called the cornea, is too curved. This causes light rays to focus at a point in front of the light-sensitive tissue at the back of the eye (retina) instead of directly on it.

Nearsightedness tends to worsen very slowly over time. Usually, it can be completely corrected with glasses, contact lenses, or surgery.

What is the cause?

The eyeball grows as the rest of the body grows. Sometimes the eyeball grows too long and becomes oval-shaped. This often becomes a problem between the ages of 8 and 12, but it can show up earlier or later.

Some experts think that nearsightedness is something you are born with. Some think it is caused by the stress of too much reading, close work, or computer use. It is likely that both factors play a role in this problem.

In older age, nearsightedness can be caused by cataracts. Cataracts can be removed and replaced with a clear plastic lens.

Nearsightedness may also be caused by a cornea that is too curved. This can be a problem you have had since birth or caused by diseases of the cornea.

If you have extreme nearsightedness (called high myopia), you are at risk for more serious eye problems such as retinal detachment, degeneration of the retina, and bleeding under the macula. If you are very nearsighted, you should see an eye care provider regularly for checkups.

What are the symptoms?

The major symptoms of nearsightedness are:

• blurred vision
• eye discomfort
• eyestrain

How is it diagnosed?

• Your eye care provider will ask you to read letters or numbers on a chart. This test measures your ability to see distant objects clearly.
• Usually, your provider will dilate your eyes by putting some eyedrops in them. Then he or she will look at your retinas through a lighted instrument called an ophthalmoscope.
• Your provider will have you look through various lenses like those in glasses to see which ones give you the best distance vision.

How is it treated?

Nearsightedness can be corrected with eyeglasses, contact lenses, or by surgery.

Corrective lenses:

Glasses or contact lenses can help the eyeball to focus light rays properly on the retina. Both have advantages and disadvantages. People may choose contact lenses for comfort and looks. Contacts also may allow better side vision, especially if you need lenses that give a lot of correction.

Surgery:

Two types of surgery are most commonly done to correct nearsightedness:

• PRK (laser photorefractive keratectomy): In this surgery a laser removes tissue from the surface of the cornea.
• LASIK: In this procedure a laser removes tissue from an inner layer of the cornea after the outer layer is cut and held aside. This is the most common procedure.

Both of these procedures flatten the cornea. If successful, they correct nearsightedness permanently. They have a high success rate when done properly. These procedures are not recommended for every case of nearsightedness.

Other surgical procedures to correct nearsightedness include clear lens exchange, corneal ring implant, and implantable contact lenses. Check with your provider to see if any of these might be right for you.

How can I take care of myself?

• Prevent eyestrain by using the right amount of light for reading or doing close work. Talk to your healthcare provider about what type of light is best for your eyes.
• Wear your glasses as prescribed.
• Rest your eyes often if you read, do close work, or use a computer for long periods.
• Have your eyes checked regularly to see if other problems develop or if you need a stronger prescription for your glasses or contacts.

How can I help prevent nearsightedness?

Nearsightedness cannot be prevented. You may be able to help prevent vision problems from becoming severe if you have regular eye exams.