Myopia (cont.)
What Causes Myopia?
People who are nearsighted have what is called a refractive
error. This means that the light rays bend incorrectly into the
eye to transmit images to the brain. In people with myopia, the
eyeball is too long or the cornea has too much curvature, so the
light entering the eye is not focused correctly. Light rays of
images focus in front of the retina, the light-sensitive part of
the eye, rather than directly on the retina, causing blurred
vision.
Myopia
runs in families and usually appears in childhood. Sometimes the
condition plateaus, or sometimes it worsens with age.
What Are the Symptoms of Myopia?
People who are nearsighted often complain of headaches,
eyestrain, squinting or fatigue when driving, playing sports, or
looking more than a few feet away.
How Is Myopia Diagnosed?
Myopia can be easily diagnosed using standard eye exams given
by an eye doctor.
How Is Myopia Treated?
Glasses, contact lenses, or 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.
Refractive surgery can reduce or even eliminate your
dependence on glasses or contact lenses. The most common
procedures for myopia are performed with a laser, including:
- Photorefractive keratectomy. Also called PRK , 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 cut a flap through the top
of the cornea, a laser removes some corneal tissue, then the
flap is dropped back into place. LASIK is the most common
surgery used to correct nearsightedness.
- Corneal rings. Plastic corneal rings, called
Intacs, are implanted into the eye to alter the shape of the
cornea. One advantage of the rings is that they may be left
in place permanently, may be removed in case of a problem,
or adjusted should a prescription change be necessary.
Reviewed by the doctors at
The Cleveland Clinic Cole Eye Institute.
Edited by
Charlotte E. Grayson, MD,
WebMD, October 2004.
Last Editorial Review: 6/21/2005
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