Astigmatism (eye)
= Astigmatism
{disambiguate=eye}
{wiki=Astigmatism}
= Ocular astigmatism
{synonym}
An ocular <refractive error> in which a point object cannot be brought to one sharp retinal focus by a single spherical correction. <Regular ocular astigmatism> has perpendicular principal meridians of unequal power; irregular departures require a more general description.<Astigmatism by the National Eye Institute>[Overview and correction]{ref}