astigmatismn.

Brit.

/əˈstɪɡmətɪz(ə)m/, U.S.

/əˈstɪɡməˌtɪzəm/

Etymology: Formed as astigmatic adj. + -ism suffix.

a. A structural defect in the eye (see quot.), which prevents the rays of light from being brought to a common focus on the retina.

ΘΚΠ

the world > health and disease > ill health > a disease > disorders of eye > disordered vision > [noun] > astigmatism

astigmatism1849

1849 G. B. Airy in Trans. Cambr. Philos. Soc. 8 361 Twenty years ago, I had the honour of submitting to this Society a statement of the effects of a mal-formation in my own left eye. The nature of the effect was this: that the rays of light coming from a luminous point and falling upon the whole surface of the pupil do not converge to a point at any position within the eye, but converge in such a manner as to pass through two lines at right angles to each other, (a geometrical phenomenon, to which the term astigmatism was very happily affixed by the present Master of Trinity College [Whewell]).

1862 J. Laurence in Med. Times 1 Nov. 474/1 Correction both of the astigmatism and the ametropia.

1878 M. Foster Text Bk. Physiol. (ed. 2) iii. ii. 411 The cause of astigmatism is..unequal curvature of the cornea.

b. Optics. A similar defect in a lens.

ΘΚΠ

the world > physical sensation > sight and vision > optical instruments > lens > [noun] > qualities of lenses

power1673

refracting angle1676

resolution1831

depth of focus1852

astigmatism1859

aplanatism1869

apochromatism1887

covering power1895

coverage1936

asphericity1944

parfocality1955

1859 S. Parkinson Treat. Optics iv. 48 When a pencil of rays is reflected or refracted at the surface of a medium, the reflected or refracted rays will not, in general, pass accurately through one point. This peculiarity is sometimes called astigmatism.

1892 J. T. Taylor Optics Photogr. xxiii Astigmatism is a serious fault for a lens to possess in any marked degree.

2. figurative.

ΘΚΠ

the mind > mental capacity > thought > absence of thought > [noun] > confusion of thought

mysticism1722

astigmatism1934

1934 G. Bottomley in Ess. & Stud. XIX. 142 This mental astigmatism..was not noticed while the fires of great genius flamed high.

This entry has not yet been fully updated (first published 1885; most recently modified version published online March 2022).

单词	astigmatism
释义	astigmatismn. Brit. /əˈstɪɡmətɪz(ə)m/, U.S. /əˈstɪɡməˌtɪzəm/ Etymology: Formed as astigmatic adj. + -ism suffix. 1. a. A structural defect in the eye (see quot.), which prevents the rays of light from being brought to a common focus on the retina. ΘΚΠ the world > health and disease > ill health > a disease > disorders of eye > disordered vision > [noun] > astigmatism astigmatism1849 1849 G. B. Airy in Trans. Cambr. Philos. Soc. 8 361 Twenty years ago, I had the honour of submitting to this Society a statement of the effects of a mal-formation in my own left eye. The nature of the effect was this: that the rays of light coming from a luminous point and falling upon the whole surface of the pupil do not converge to a point at any position within the eye, but converge in such a manner as to pass through two lines at right angles to each other, (a geometrical phenomenon, to which the term astigmatism was very happily affixed by the present Master of Trinity College [Whewell]). 1862 J. Laurence in Med. Times 1 Nov. 474/1 Correction both of the astigmatism and the ametropia. 1878 M. Foster Text Bk. Physiol. (ed. 2) iii. ii. 411 The cause of astigmatism is..unequal curvature of the cornea. b. Optics. A similar defect in a lens. ΘΚΠ the world > physical sensation > sight and vision > optical instruments > lens > [noun] > qualities of lenses power1673 refracting angle1676 resolution1831 depth of focus1852 astigmatism1859 aplanatism1869 apochromatism1887 covering power1895 coverage1936 asphericity1944 parfocality1955 1859 S. Parkinson Treat. Optics iv. 48 When a pencil of rays is reflected or refracted at the surface of a medium, the reflected or refracted rays will not, in general, pass accurately through one point. This peculiarity is sometimes called astigmatism. 1892 J. T. Taylor Optics Photogr. xxiii Astigmatism is a serious fault for a lens to possess in any marked degree. 2. figurative. ΘΚΠ the mind > mental capacity > thought > absence of thought > [noun] > confusion of thought mysticism1722 astigmatism1934 1934 G. Bottomley in Ess. & Stud. XIX. 142 This mental astigmatism..was not noticed while the fires of great genius flamed high. This entry has not yet been fully updated (first published 1885; most recently modified version published online March 2022). < n.1849
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