[uh-stig-muh-tiz-uh
m] 
| 1. | Also called a⋅stig⋅mi⋅a [uh-stig-mee-uh] . Ophthalmology. 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. | Optics. an aberration of a lens or other optical system in which the image of a point is spread out along the axis of the system. |
| 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-1 + Greek stigma, stigmat-, point (from stizein, stig-, to tattoo; see steig- in Indo-European roots).] as'tig·mat'ic (ās'tĭg-māt'ĭk) adj. & n., as'tig·mat'i·cal·ly adv. |
astigmatism a·stig·ma·tism (ə-stĭg'mə-tĭz'əm)
n.
A condition in which unequal curvatures along the different meridians in one or more of the refractive surfaces of the eye cause the rays from a light source not to be focused at a single point on the retina. Also called astigmia.