| 单词 | astigmatism |
| 释义 | astigmatism (once / 57099 pages) n The eye has a cornea — a clear, curved layer that protects it. If the cornea's shape is irregular, astigmatism results. People who have astigmatism see images as distorted, so they need to wear glasses or contact lenses. Sometimes people mistakenly say, "One of my eyes has a stigmatism." But the a in astigmatism is important to its meaning. The prefix a- means "without." Stigma is Greek for "point," so an eye that is "without point" is one that doesn't allow light rays to meet at a single point or focus. Since astigmatism is a condition, you don't need the article an before it: "My eye has astigmatism," not "My eye has an astigmatism." WORD FAMILYastigmatic: astigmatism+/astigmia: astigmatic USAGE EXAMPLESAbout the same time, manufactures produced a lens that could fix astigmatism. Washington Times(Oct 01, 2016) Lasik is used to treat the common vision problems nearsightedness, farsightedness, and astigmatism. Time(Sep 01, 2016) Ellison, who had myopic astigmatism, a form of nearsightedness, pulled the baton out of McCrillis’s hand. Washington Post(May 06, 2016) 1n (ophthalmology) impaired eyesight resulting usually from irregular conformation of the cornea; common in nearsighted people Syn|Hypo|Hyper astigmia keratectasia abnormal bulging of the cornea of the eye keratoconusabnormal cone-shaped protrusion of the cornea of the eye; can be treated by epikeratophakia ametropia (ophthalmology) faulty refraction of light rays in the eye as in astigmatism or myopia 2n (optics) defect in an optical system in which light rays from a single point fail to converge in a single focal point Syn|Ant|Hyper astigmia stigmatism (optics) condition of an optical system (as a lens) in which light rays from a single point converge in a single focal point condition, status a state at a particular time |
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