A diagnostic technique used to detect paretic extraocular muscle, particularly the cranial nerve IV (trochlear nerve) and superior oblique muscle in acquired vertical double vision. It can also diagnose the vertical rectus muscle palsy or inferior oblique and help differentiate dissociated vertical divergence from other vertical strabismus.

Also Known As

  • The Parks–Bielschowsky Three-Step Test
  • Park's Three-Step Test
  • Bielschowsky Head Tilt Test