Horizontal Gaze Nystagmus

Clues:

1.  Lack of smooth pursuit in left eye.

2.  Lack of smooth pursuit in right eye.

3.  Distinct and sustained nystagmus at maximum deviation in left eye.

4.  Distinct and sustained nystagmus at maximum deviation in right eye.

5.  Onset of nystagmus prior to 45 degrees in left eye.

6.  Onset of nystagmus prior to 45 degrees in right eye.

Instructions:

1.  I am going to check your eyes.  Please remove your glasses.

2.  Keep you head still and follow the stimulus with your eyes only

3.  Do not move your head.

4.  Do you understand the instructions?

5.  Position the stimulus:

  • approximately 12-15 inches from the suspect’s nose
  • slightly above eye level

6.   Check eyes for:

  • equal pupil size
  • resting nystamus
  • equal tracking

7.  Smooth Pursuit

  • Start with left eye
  • Move stimulus to right at speed that requires approximately two seconds to bring the suspect’s eyes as far to the side as it can go.
  • Determine whether eye was able to pursue smoothly.
  • Move stimulus all the way to the left, back across the suspect’s face checking if the right eye pursues smoothly.
  • Movement of the stimulus should take approximately two seconds out and two second back for each eye.
  • Repeat the procedure.

8.  Distinct and sustained nystagmus at maximum deviation

  • Start with left eye
  • Move the object to the suspect’s left side until the eye has gone as far to the side as possible.  (Usually, no white will be showing in the corner of the eye at maximum deviation.
  • Hold the eye at that position for a minimum of four seconds.
  • Observe the eye for distinct and sustained nystagmus.
  • Move the stimulus all the way across the suspect’s face to check the right eye holding that position for a minimum of four seconds.
  • Repeat the procedure.

9.  Onset of nystagmus prior to 45 degrees

  • Start with left eye.
  • Move the stimulus four seconds to the left to reach the edge of the suspect’s left shoulder.
  • Watch the eye carefully for any jerking.
  • If/when you see it, stop and verify that the jerking continues.
  • Move the stimulus to the left four second to reach the edge of the suspect’s right shoulder.
  • Watch the eye carefully for any jerking.
  • If/when you see it, stop and verify that the jerking continues.
  • Repeat the procedure.

For more general information on the Standardized Field Sobriety Tests, please click here.