OHSU

Casey Eye Institute at OHSU, Portland, Oregon

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Myopia

Myopia, or nearsightedness, affects many people. Being nearsighted makes it difficult to see things clearly at a distance. This eye condition is easily corrected with eyeglasses, contact lenses or surgery.

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What Causes Myopia?

People who are nearsighted have what is called a refractive error. In people with myopia, the eyeball is too long or the cornea is curved too much for light entering the eye to focus where it should. If you are nearsighted, images focus in front of the retina (the part of the eye that sees light and fine details) instead of directly on it. This causes blurry vision.

Myopia runs in families and usually appears in childhood. It usually plateaus, or stops getting worse, after a certain point. However, it can get worse with age.

Symptoms

People who are nearsighted often complain of headaches, eye strain or having to squint to see things well. If you are nearsighted, your eyes may get tired when you are driving, playing sports or looking more than a few feet away. Children who are nearsighted often complain of not being able to see the board at school.

Treatment

Glasses, contact lenses and refractive surgery can correct myopia.

With myopia, your prescription for glasses or contact lens is a negative number, such as -3.00. The higher the number, the stronger your lenses will be. The prescription helps the eye focus light rays on the retina, making vision clearer.

Refractive surgery can reduce or even eliminate your dependence on glasses or contact lenses. The most common procedures for myopia include:

  • Photorefractive keratectomy, also called PRK. In this procedure, a laser is used to remove a layer of corneal tissue, which flattens the cornea and allows light rays to focus closer to or even on the retina.

  • Laser-assisted in situ keratomileusis, commonly called LASIK. A laser is used to create a flap on the top of the cornea. The laser removes some corneal tissue before the flap is replaced. LASIK is the most common surgery for nearsightedness.