Online Google Dictionary

astigmatism 中文解釋 wordnet sense Collocation Usage Collins Definition
Noun
/əˈstigməˌtizəm/,
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A defect in the eye or in a lens caused by a deviation from spherical curvature, which results in distorted images, as light rays are prevented from meeting at a common focus,
  1. A defect in the eye or in a lens caused by a deviation from spherical curvature, which results in distorted images, as light rays are prevented from meeting at a common focus

  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
  3. (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
  4. An optical system with astigmatism is one where rays that propagate in two perpendicular planes have different foci. If an optical system with astigmatism is used to form an image of a cross, the vertical and horizontal lines will be in sharp focus at two different distances. ...
  5. Astigmatism is an optical defect in which vision is blurred due to the inability of the optics of the eye to focus a point object into a sharp focused image on the retina. This may be due to an irregular or toric curvature of the cornea or lens. ...
  6. 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; 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
  7. Distorted vision typically caused by an irregular shaped cornea. When the cornea is not perfectly spherical in shape, two different points of focus may be formed in the same eye, creating distorted and blurred vision. ...
  8. Structural defects of the eye in which the light rays from a viewed object do not meet in a single focal point, resulting in blurred images being sent to the brain. An astigmatic cornea is not perfectly rounded like a basketball but has an irregular shape more like the side of a football. ...
  9. Astigmatism is one of a group of eye conditions known as refractive errors. Refractive errors cause a disturbance in the way that light rays are focused within the eye. Astigmatism often occurs with nearsightedness and farsightedness, conditions also resulting from refractive errors. ...
  10. a distortion of the image on the retina caused by irregularities in the cornea or lens.
  11. An additional curvature on the surface of the cornea, or lens of the eye, that makes it difficult to focus. Slight degrees can cause headaches, fatigue, and poor schoolwork. More serious degrees produce blurred vision at all distances. ...
  12. a vision problem that results in blurred images.
  13. light rays entering the eye do not all meet at the same point (similar to a frayed string), which results in blurred or distorted vision. An abnormally shaped cornea typically causes this condition. Occasionally astigmatism exists in the lens of the eye. ...
  14. lens aberration making a single point light source impossible to focus as a true point.
  15. An optical defect that causes light rays from an off-axis point to form images at different positions.
  16. Condition in which the cornea's curvature is asymmetrical (the eye is shaped like a football or egg instead of a baseball); light rays are focused at two points on the retina rather than one, resulting in blurred vision. ...
  17. A warping of the curvature of the cornea so that light rays entering the eye do not meet in a single focal point, resulting in a distorted image.
  18. (uh-STIG-muh-tiz-um). Refractive error. 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. ...
  19. The uneven foreground and background blue that is in an image.
  20. A condition that occurs when an uneven curvature of the eye causes light to be refracted (bent) unevenly, resulting in distorted vision.
  21. A vision condition that causes blurred vision due either to the irregular shape of the cornea, the clear front cover of the eye, or sometimes the curvature of the lens inside the eye.
  22. An eye disorder caused by uneven curvature of the eyeball that motivates light rays to bend, targeting more than one point of the retina, instead of a single spot. This causes blurry vision, vague shadows on characters when reading, and slight double vision.
  23. Distorted spot resulting from imperfect focus caused by a defect of an optical system.
  24. An optical aberration resulting from unequal magnification across different diameters.
  25. an electron-optical lens aberration that causes the defocus to be a function of azimuth, and the contrast transfer function to deviate from circular symmetry about the optical axis. ...