astigmatism /astig·ma·tism/ (ah-stig´mah-tizm) ametropia caused by differences in curvature in different meridians of the refractive surfaces of the eye so that light rays are not sharply focused on the retina.astigmat´ic 
)
Astigmatism: the appearance of lines as seen by (A) the normal eye and (B) the astigmatic eye.
compound astigmatism that complicated with hypermetropia or myopia in all meridians.
corneal astigmatism that due to irregularity in the curvature or refracting power of the cornea.
irregular astigmatism that in which the curvature varies in different parts of the same meridian or in which refraction in successive meridians differs irregularly.
mixed astigmatism that in which one principal meridian is myopic and the other hyperopic.
myopic astigmatism that in which the light rays are brought to a focus in front of the retina.
regular astigmatism that in which the refractive power of the eye shows a uniform increase or decrease from one meridian to another.
| corneal astigmatism n. Astigmatism due to a defect in the curvature of the corneal surface. |
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