Definitions

from The American Heritage® Dictionary of the English Language, 4th Edition

  • n. 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.

from Wiktionary, Creative Commons Attribution/Share-Alike License

  • n. A defect of a lens such that light rays coming from a point do not meet at a focal point so that the image is blurred.
  • n. A disorder of the vision, usually due to a misshapen cornea, such that light does not focus correctly on the retina causing a blurred image.

from the GNU version of the Collaborative International Dictionary of English

  • n. A defect of the eye or of a lens, in consequence of which the rays derived from one point are not brought to a single focal point, thus causing imperfect images or indistinctness of vision.

from The Century Dictionary and Cyclopedia

  • n. In ophthalmology, a defect in the refractive apparatus of the eye, the curvature of the refracting surfaces being greater along certain meridians than along others, so that rays of light proceeding from an external point do not converge to a point upon the retina, but to a line.
  • n. A similar defect in a lens.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

  • n. (optics) defect in an optical system in which light rays from a single point fail to converge in a single focal point
  • n. (ophthalmology) impaired eyesight resulting usually from irregular conformation of the cornea; common in nearsighted people

Etymologies

a-1 + Greek stigma, stigmat-, point (from stizein, stig-, to tattoo; see steig- in Indo-European roots).
(American Heritage® Dictionary of the English Language, Fourth Edition)
From a- ("not") + stem of Ancient Greek στίγμα (stigma, "mark, point") +‎ -ism (Wiktionary)

Examples

  • After the surgery, I definitely saw better - my previous vision had been -7 and -7.5 with severe astigmatism, which is a short step away from being totally non-functional - but after two weeks, I went back in for another corrective round.

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  • If your eye is squished on one side, called an astigmatism, your lenses should compensate for that.

    You Being Beautiful

  • There is an optical condition of the eye known as astigmatism, in which the cornea is usually at fault.

    A Practical Physiology

  • Another defect of the eye, known as astigmatism, is due to the fact that the eye does not always have a perfectly spherical front (cornea).

    The Science of Human Nature A Psychology for Beginners

  • * '' 'Astigmatism:' '' An astigmatism occurs when the cornea or lens (or both) are not perfectly symmetrical.

    CreationWiki - Recent changes [en]

  • Astigmatism: An astigmatism occurs when the cornea or lens (or both) are not perfectly symmetrical.

    CreationWiki - Recent changes [en]

  • That produces a condition called astigmatism, the effect of which is to make images appear blurry whether near or far.

    xml's Blinklist.com

  • My solution was to make sure you get a scope with the "astigmatism" adjustment.

    On Gun Sights and Eye Doctors

  • So long as the minds that perceive them are not affected by superficial or deepest causes for deceptive or distorted appearance-making – such as astigmatism, autism, or grasping for true unimputed existence – the cognitions of the appearances of us as usual humans or as Buddha-figures are equally valid.

    7 Non-Gelug Variations Concerning General Tantra

  • What is known as reflex nervousness arises as a result of minor local conditions, such as astigmatism and other eye conditions, trouble with the nose and throat and trouble with the organs of generation.

    The Nervous Housewife

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