astigmatism

definition: (optics) defect in an optical system in which light rays from a single point fail to converge in a single focal point
example:
speech part: noun
synonyms: astigmia
definition: (ophthalmology) impaired eyesight resulting usually from irregular conformation of the cornea
example:
speech part: noun
synonyms: astigmia

How astigmatism is being used?