astig·​ma·​tism | \ ə-ˈstig-mə-ˌti-zəm How to pronounce astigmatism (audio) \

Definition of astigmatism

1 : a defect of an optical system (such as a lens) causing rays from a point to fail to meet in a focal point resulting in a blurred and imperfect image
2 : a defect of vision due to astigmatism of the refractive system of the eye and especially to corneal irregularity
3 : distorted understanding suggestive of the blurred vision of an astigmatic person

Examples of astigmatism in a Sentence

Recent Examples on the Web Myopia will likely play a big part in that—some experts predict 5 billion people worldwide will have myopia by 2050, which would put even bigger demands on contacts to be able to address strong prescriptions and astigmatism. Alexandra Ossola, Quartz, 15 Sep. 2021 Functional vision goes way beyond simple problems such as nearsightedness, farsightedness and astigmatism, instead relating to the way the eyes function together and send visual information to the brain for processing. Melanie Savage,, 16 Aug. 2020 The system will address everything from astigmatism, to farsightedness, and nearsightedness, according to Patently Apple, which first spotted the patents. Courtney Linder, Popular Mechanics, 12 July 2020 These are simply garden-variety nearsightedness and farsightedness as well as astigmatism (distorted vision at all distances) and presbyopia, which is the loss of up-close focusing ability (hello, reading glasses!). Meryl Davids Landau, Good Housekeeping, 13 Mar. 2020 According to the Mayo Clinic, common side effects of laser eye surgery include dry eyes and temporary vision disturbances, with some patients more rarely affected by under- or over-corrections, astigmatisms and even potential loss of eyesight. Benjamin Vanhoose,, 14 Nov. 2019 But my mother has wanted to be an astronaut all of her life and couldn’t because of an astigmatism. John Wenzel, The Know, 13 Oct. 2019 Contact lenses can be worn to correct a variety of vision conditions, such as myopia, or nearsightedness; hyperopia, or farsightedness; and astigmatism. Tiffany Yannetta, Seventeen, 26 Oct. 2018 But these astigmatism-correcting lenses can be implanted during traditional or laser surgery, Akpek said. Sarah Gantz,, 21 Mar. 2018

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'astigmatism.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of astigmatism

1831, in the meaning defined at sense 1

History and Etymology for astigmatism

a- entry 2 + Greek stigmat-, stígma "mathematical point, mark, tattoo mark" (more usually stigmḗ in this sense; referring to the point on the retina at which light rays converge in a normal eye) + -ism — more at stigma

Note: The term astigmatism was introduced by the British astronomer George Biddell Airy (1801-92), who performed a pioneering measurement and description of an astigmatism in his own eye ("On a Peculiar Defect of the Eye and a Mode of Correcting It," Transactions of the Cambridge Philosophical Society, vol. 2 [1827], pp. 267-71). Airy did not use the word in the article, however, and it does not seem to appear under his name until a much later article on the same subject, "On a Change in the State of an Eye affected with a Mal-formation [Read May 25, 1846]," Transactions of the Cambridge Philosophical Society, vol. 8 (1849), pp. 361-62. In the latter article Airy describes "the nature of the effect" as "a geometrical phenomenon, to which the term astigmatism was very happily affixed by the present Master of Trinity College." The "Master of Trinity College," Cambridge, was the clergyman and polymath William Whewell (1794-1866), to whom a number of other scientific neologisms are credited. The word was evidently in oral circulation prior to Airy's use of it in print; in 1831, an unsigned article in The British Critic, Quarterly Theological Review, and Eccesiastical Record (vol. 9, p. 82) mentions astigmatism, "employing a word which we believe Professor Airy is in the habit of using in his lectures on this subject [optics]." For details on Airy and astigmatism, see John R. Levene, "Sir George Biddell Airy, F.R.S. (1801-1892) and the Discovery and Correction of Astigmatism," Notes and Records of the Royal Society of London, Vol. 21, No. 2 (December, 1966), pp. 180-199.

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The first known use of astigmatism was in 1831

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Last Updated

25 Sep 2021

Cite this Entry

“Astigmatism.” Dictionary, Merriam-Webster, Accessed 22 Oct. 2021.

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English Language Learners Definition of astigmatism

: a problem with the eye that prevents a person from seeing clearly


astig·​ma·​tism | \ ə-ˈstig-mə-ˌtiz-əm How to pronounce astigmatism (audio) \

Medical Definition of astigmatism

1 : a defect of an optical system (as a lens) causing rays from a point to fail to meet in a focal point resulting in a blurred and imperfect image
2 : a defect of vision due to astigmatism of the refractive system of the eye and especially to corneal irregularity — compare emmetropia, myopia


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