Correct answer has been posted in the comments by Tanya

The nurse is explaining cryotherapy to a client who has a detached retina. The nurse should explain that the MAJOR purpose of cryotherapy in the treatment of detached retina is to

  1. create a scar that promotes healing
  2. disintegrate debris in the eye
  3. freeze small blood vessels
  4. halt secretions of the lacrimal duct