Parks Three Step Tool

  • Superior Rectus (RSR)
  • Superior Oblique (RSO)
  • Inferior Oblique (RIO)
  • Inferior Rectus (RIR)
  • Superior Rectus (LSR)
  • Superior Oblique (LSO)
  • Inferior Oblique (LIO)
  • Inferior Rectus (LIR)

Left Hyper Right Hyper Which eye is hyper deviated in primary gaze?

Left Gaze Right Gaze Is the vertical deviation greater in right gaze or left gaze?

Left Tilt Right Tilt Is the vertical deviation greater with right head tilt or left head tilt?

The Parks Three Step test (also known as Parks-Bielschowsky Three Step Test or Parks-Helveston 3 Step Test) is used to isolate a paretic extraocular muscle in acquired vertical diplopia or double vision. It is not effective for assessing horizontal diplopia and is not reliable in patients with prior strabismus surgery. The test is more reliable with recent onset diplopia. By calculating the vertical deviation in primary gaze, left and right gaze, and right and left head tilt, the test isolates each muscle's primary field of action to determine the affected muscle.