four-eyes vs pair of eyeglasses

four-eyes

noun
  • A person who wears spectacles. 

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 four-eyes and pair of eyeglasses occurred in a corpus of books? (source: Google Ngram Viewer )