purblind vs unsighted

purblind

adj
  • Partially blind. 

  • Near-sighted or dim-sighted. 

  • Lacking in discernment or understanding. 

unsighted

adj
  • Without the sense of sight; blind. 

  • Not sighted; unseen. 

  • Not furnished with a sight. 

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