ASTIGMATISM

Pronunciation (US):

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IPA (US):

 Dictionary entry overview: What does astigmatism mean? 

• ASTIGMATISM (noun)
  The noun ASTIGMATISM has 2 senses:

1. (ophthalmology) impaired eyesight resulting usually from irregular conformation of the cornea; common in nearsighted people

2. (optics) defect in an optical system in which light rays from a single point fail to converge in a single focal point

  Familiarity information: ASTIGMATISM used as a noun is rare.

 Dictionary entry details 

• ASTIGMATISM (noun)

Sense 1

Meaning:

(ophthalmology) impaired eyesight resulting usually from irregular conformation of the cornea; common in nearsighted people

Classified under:

Nouns denoting stable states of affairs

Synonyms:

astigmatism; astigmia

Hypernyms ("astigmatism" is a kind of...):

ametropia ((ophthalmology) faulty refraction of light rays in the eye as in astigmatism or myopia)

Domain category:

ophthalmology (the branch of medicine concerned with the eye and its diseases)

Hyponyms (each of the following is a kind of "astigmatism"):

keratectasia (abnormal bulging of the cornea of the eye)

keratoconus (abnormal cone-shaped protrusion of the cornea of the eye; can be treated by epikeratophakia)

Derivation:

astigmatic (of or relating to a defect in the eye or in a lens caused by a deviation from spherical curvature which prevents light rays from meeting at a common focus and so results in distorted images)

Sense 2

Meaning:

(optics) defect in an optical system in which light rays from a single point fail to converge in a single focal point

Classified under:

Nouns denoting stable states of affairs

Synonyms:

astigmatism; astigmia

Hypernyms ("astigmatism" is a kind of...):

condition; status (a state at a particular time)

Domain category:

optics (the branch of physics that studies the physical properties of light)

Antonym:

stigmatism ((optics) condition of an optical system (as a lens) in which light rays from a single point converge in a single focal point)

Derivation:

astigmatic (of or relating to a defect in the eye or in a lens caused by a deviation from spherical curvature which prevents light rays from meeting at a common focus and so results in distorted images)

 Context examples 

A lens generally worn in front of the eye, mainly used to treat myopia, hyperopia, astigmatism, and presbyopia.

(Corrective Lens, NCI Thesaurus)

Representative examples include congenital cataract, congenital glaucoma, and astigmatism.

(Congenital Eye Disorder, NCI Thesaurus)