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Astigmatism is a very common and often misunderstood condition. Like nearsightedness and farsightedness, astigmatism is a refractive error, not an eye disease, and it is easily treated with eyeglasses or contact lenses.
What causes astigmatism?
Astigmatism usually is due to unequal curves of the cornea, the clear front surface of the eye. In astigmatism, the cornea isn’t perfectly round, but instead is more football- or egg-shaped.
In some cases, astigmatism is caused by unequal curves in the lens inside the eye, which is located directly behind the pupil.
In both types of astigmatism, the unequal curves of the cornea and/or lens prevent light from being focused to a clear, single image on the retina of the eye.
Signs and symptoms of astigmatism
In addition to blurred vision, common signs and symptoms of astigmatism include headaches, fatigue and eyestrain.
Astigmatism is common and usually develops in childhood. A study at the Ohio State University School of Optometry found that more than 28 percent of schoolchildren have astigmatism.
Because astigmatism can cause headaches and eyestrain during reading, children with uncorrected astigmatism sometimes avoid reading or have a short attention span when reading, which can affect their school performance.
How is astigmatism treated?
In most cases, astigmatism is treated with full-time wear of glasses or contact lenses.
Rigid gas permeable (RGP or GP) contact lenses often provide the best correction for astigmatism. But special soft contact lenses for astigmatism, called toric contact lenses, also are available.
Hybrid contact lenses — contacts with a GP optical center surrounded by a skirt of soft lens material for greater wearing comfort — are another option for astigmatism correction.
LASIK and other types of refractive surgery also can be performed to correct astigmatism.
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