Assertion: astigmatism's shape | /r/HasProperty | rotated by 90 °
Facets:
value: simply
type: MANNER
value: about vertex
type: LOCATION
Source sentences:
text: Similarly to that of the primary, the error of secondary astigmatism at either sagittal or tangential focus (left; tangential focus has the same shape simply rotated by 90 ° about vertex) is reduced by refocusing to the best focus midway between them (right).