eyeglasses vs pair of eyeglasses

eyeglasses

noun
  • Spectacles, glasses. 

pair of eyeglasses

noun
  • A pair of lenses set in a frame worn on the nose and ears in order to correct deficiencies in eyesight or to ornament the face. 

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