hyperopia vs visual acuity

hyperopia

noun
  • A disorder of the vision where the eye focusses images behind the retina instead of on it, so that distant objects can be seen better than near objects. 

visual acuity

noun
  • The sharpness of vision or sight. 

  • Strength of vision expressed on some definite scale. 

How often have the words hyperopia and visual acuity occurred in a corpus of books? (source: Google Ngram Viewer )