astigmatism


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astigmatism
top: normal eye with light focusing on the retina
bottom: astigmatic eye with light focusing in different places on or in front of the retina

a·stig·ma·tism

 (ə-stĭg′mə-tĭz′əm)
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.

[a- + Greek stigma, stigmat-, point (from stizein, stig-, to tattoo; see steig- in Indo-European roots).]

as′tig·mat′ic (ăs′tĭg-măt′ĭk) adj. & n.
as′tig·mat′i·cal·ly adv.

astigmatism

(əˈstɪɡməˌtɪzəm) or

astigmia

n
1. (General Physics) a defect of a lens resulting in the formation of distorted images; caused by the curvature of the lens being different in different planes
2. (Pathology) faulty vision resulting from defective curvature of the cornea or lens of the eye

a•stig•ma•tism

(əˈstɪg məˌtɪz əm)

n.
1. Also called a•stig•mi•a (əˈstɪg mi ə) a refractive error of the eye in which parallel rays of light from an external source do not converge on a single focal point on the retina.
2. an aberration of a lens or other optical system in which the image of a point is spread out along the axis.
[1840–50]

a·stig·ma·tism

(ə-stĭg′mə-tĭz′əm)
A defect of the eye in which the curvature of the cornea or lens is uneven. This prevents rays of light from being focused at a single point on the retina, resulting in indistinct or imperfect images.

astigmatism

a defect in a lens, eye, or mirror that causes rays from one direction not to focus at one point. — astigmatic, adj.
See also: Eyes
ThesaurusAntonymsRelated WordsSynonymsLegend:
Noun1.astigmatism - (ophthalmology) impaired eyesight resulting usually from irregular conformation of the cornea; common in nearsighted people
ophthalmology - the branch of medicine concerned with the eye and its diseases
ametropia - (ophthalmology) faulty refraction of light rays in the eye as in astigmatism or myopia
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
2.astigmatism - (optics) defect in an optical system in which light rays from a single point fail to converge in a single focal point
optics - the branch of physics that studies the physical properties of light
condition, status - a state at a particular time; "a condition (or state) of disrepair"; "the current status of the arms negotiations"
stigmatism - (optics) condition of an optical system (as a lens) in which light rays from a single point converge in a single focal point
Translations

astigmatism

[æsˈtɪgmətɪzəm] Nastigmatismo m

astigmatism

[əˈstɪgmətɪzəm] nastigmatisme m

astigmatism

astigmatism

[æsˈtɪgmətɪzm] nastigmatismo

a·stig·ma·tism

[MIM*603047]
n. astigmatismo, defecto de la visión a causa de una irregularidad en la curvatura del ojo.

astigmatism

n astigmatismo
References in periodicals archive ?
Radial Keratotomy (RK), Astigmatic Keratotomy (AK), and Automated Lamellar Keratoplasty (ALK), are commonly performed procedures selected by people who want to be less dependent on glasses or contact lenses for the correction or improvement of myopia (nearsightedness), hyperopia (farsightedness), and astigmatism.
Food and Drug Administration (FDA) has approved wavefront-guided and mixed astigmatism indications for the ALLEGRETTO WAVE Eye-Q system.
Optik Mizen has launched a new varifocal lens that has been designed to achieve more natural vision for patients with astigmatism.
The results add a new piece of evidence to a longstanding debate as to how or whether the lens or other eye structures change in response to focusing abnormalitiesespecially those caused by irregular shape of the eye, or astigmatism.
3] SICS and phacoemulsification have advantages like early visual rehabilitation, less induced astigmatism and no suture-related complications as wound constriction and closure.
Among various refractive errors, astigmatism was found in 41% cases, hypermetropia in 22%, and myopia in 12% patients.
Objective: To assess the frequency of amount and axis of astigmatism with respect to age and gender.
As well as making reading hard, people with an astigmatism will have problems with both near as well as distant vision.
While hyperopia and astigmatism did not vary among race and ethnicity categories, myopia prevalence was higher at 38.
Studies of challenging cases include CK for plano presbyopes, over-corrections, correction of astigmatism and postcataract astigmatism, and for treatment of keratoconus.