Astigmatism
WordNet
noun
(1) (optics) defect in an optical system in which light rays from a single point fail to converge in a single focal point
(2) (ophthalmology) impaired eyesight resulting usually from irregular conformation of the cornea
WiktionaryText
Noun
- 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.