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astigmatism

[uh-stig-muh-tiz-uh m] /əˈstɪg məˌtɪz əm/
noun
1.
Also called astigmia
[uh-stig-mee-uh] /əˈstɪg mi ə/ (Show IPA)
. Ophthalmology. a refractive error of the eye in which parallel rays of light from an external source do not converge on a single focal point on the retina.
2.
Optics. an aberration of a lens or other optical system in which the image of a point is spread out along the axis of the system.
Origin
1840-1850
1840-50; astigmat(ic) + -ism
Dictionary.com Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2014.
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British Dictionary definitions for astigmia

astigmatism

/əˈstɪɡməˌtɪzəm/
noun
1.
a defect of a lens resulting in the formation of distorted images; caused by the curvature of the lens being different in different planes
2.
faulty vision resulting from defective curvature of the cornea or lens of the eye
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
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Word Origin and History for astigmia

astigmatism

n.

1849, coined by the Rev. William Whewell (1794-1866), English polymath, from Greek a- "without" (see a- (3)) + stigmatos genitive of stigma "a mark, spot, puncture" (see stick (v.)).

Online Etymology Dictionary, © 2010 Douglas Harper
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astigmia in Medicine

astigmia a·stig·mi·a (ə-stĭg'mē-ə)
n.
See astigmatism.

astigmatism a·stig·ma·tism (ə-stĭg'mə-tĭz'əm)
n.
A condition in which unequal curvatures along the different meridians in one or more of the refractive surfaces of the eye cause the rays from a light source not to be focused at a single point on the retina. Also called astigmia.


as'tig·mat'ic (ās'tĭg-māt'ĭk) adj. & n.
The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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astigmia in Science
astigmatism
  (ə-stĭg'mə-tĭz'əm)   

A visual defect in which the unequal curvature of one or more refractive surfaces of the eye, usually the cornea, prevents light rays from focusing clearly at a single point on the retina, resulting in blurred vision.
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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astigmia in Culture
astigmatism [(uh-stig-muh-tiz-uhm)]

A condition in which the curvature of the cornea of the eye is uneven, causing a blurring of vision. Astigmatism is normally corrected by glasses.

The American Heritage® New Dictionary of Cultural Literacy, Third Edition
Copyright © 2005 by Houghton Mifflin Company.
Published by Houghton Mifflin Company. All rights reserved.
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