astigmatism

[ uh-stig-muh-tiz-uhm ]

noun
  1. Also called a·stig·mi·a [uh-stig-mee-uh]. /əˈstɪg mi ə/. 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 of astigmatism

1
First recorded in 1840–50; astigmat(ic) + -ism

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British Dictionary definitions for astigmatism

astigmatism

astigmia (əˈstɪɡmɪə)

/ (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

Scientific definitions for astigmatism

astigmatism

[ ə-stĭgmə-tĭz′əm ]


  1. 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 © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

Cultural definitions for astigmatism

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 New Dictionary of Cultural Literacy, Third Edition Copyright © 2005 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.