Disease or Syndrome
astigmatism Audio
a·stig·ma·tism [ uh-stig-muh-tiz-uhm ]
Subclass of:
Refractive Errors
Etymology:
Greek a = not + stigma = a point
Hence a failure of the light rays to focus.
Definitions related to astigmatism:
  • A type of refraction error associated with abnormal curvatures on the anterior and/or posterior surface of the cornea.
    Human Phenotype Ontology (HPO)
    The Human Phenotype Ontology Project, 2025
  • Blurry vision caused by an irregular curve in the cornea of the eye.
    Harvard Dictionary of Health Terms
    Harvard Medical Publishing, 2011
  • Optical defect in which refractive power is not uniform in all directions (meridians); light rays entering the eye are bent unequally by different meridians, which prevents formation of a sharp image focus on the retina.
    CRISP Thesaurus
    National Institutes of Health, 2006
  • Unequal or irregular curvature of the CORNEA (Corneal astigmatism) and/or the EYE LENS (Lenticular astigmatism) resulting in REFRACTIVE ERROR.
    NLM Medical Subject Headings
    U.S. National Library of Medicine, 2025
  • Astigmatism (uh-STIG-muh-tiz-um) is a common and generally treatable imperfection in the curvature of your eye that causes blurred distance and near vision.
    Mayo Clinic
    Mayo Foundation for Medical Education and Research, 2025
  • Astigmatism is a refractive error characterized by a variation in the dioptric power of the eye from one meridian to another. Instead of having a spherical cross-section, the cornea and/or lens is cylindrical, with different focal power depending on the plane in which the light travels (the meridian). The meridians that have the greatest...
    Epocrates
    Athenahealth, Inc., 2019
  • Astigmatism, nonuniform curvature of the cornea (the transparent, dome-shaped tissue located in front of the iris and pupil) that causes the eye to focus images at different distances, depending on the orientation of light as it strikes the cornea. The effect of astigmatism can also be produced by...
    Encyclopedia Britannica
    Encyclopedia Britannica, Inc., 2025
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