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 one point on the retina, resulting in blurred vision.
[A–1 + Greekstigma, stigmat-, point (fromstizein, stig-, to tattoo; see steig- in the Appendix of Indo-European roots).]
as′tig·matic(ăs′tĭg-mătĭk)adj. & n.
(click for a larger image)astigmatism
top: normal eye with light focusing on the retina
bottom: astigmatic eye with light focusing in different places on or in front of the retina
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2018 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Indo-European & Semitic Roots Appendices
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