astigmatism

noun

astig·​ma·​tism ə-ˈstig-mə-ˌti-zəm 

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

The machine can see how the eyes are focusing to check for conditions such as nearsightedness, farsightedness and astigmatism. —Nicole Villalpando, Austin American-Statesman, 12 Dec. 2024

They can also be paired with a magnetic prescription lens frame for those with severe astigmatism or have a prescription greater than -5.00D. —Christina Liao, Forbes, 29 Nov. 2024

John was later derailed by astigmatism, which also required surgery. —Daniel Brown, The Athletic, 26 Apr. 2024

Nearsightedness, farsightedness, and astigmatism are other forms of refractive errors. —Maxine Lipner, Verywell Health, 23 Oct. 2024

Word History

Etymology

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.

First Known Use

1831, in the meaning defined at sense 1

Kids Definition

astigmatism

noun

astig·​ma·​tism ə-ˈstig-mə-ˌtiz-əm 

: a defect of an optical system (as of the eye) that prevents light from focusing accurately and results in a blurred image or unclear vision

astigmatic

ˌas-tig-ˈmat-ik

adjective

Medical Definition

astigmatism

noun

astig·​ma·​tism ə-ˈstig-mə-ˌtiz-əm 

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