Practical SFST!

Question 1

What are the specific verbal commands for Horizontal Gaze Nystagmus (HGN)?

Answer 1

While keeping your weapon away from the suspect:

1. “Put your feet together, hands at your side.”
2. “Keep your head still.”
3. “I’m going to check your eyes.”
4. “Keep your head still and follow this stimulus
   with your eyes only.”
5. “Keep focusing on the stimulus until I tell you
   to stop, do you understand?”

Question 2

If you look into a subject’s eyes and notice that the two pupils are different, what could that mean?

Answer 2

> Subject has a glass eye

> Subject is suffering from a head injury or a neurological disorder

Question 3

What are the steps when conducting HGN?

Answer 3

1. Equal tracking
2. Lack of smooth tracking
3. Distinct and Sustained Nystagmus at Maximum Deviation

Question 4

How many clues do you need to acquire 88% accuracy in detecting subjects with BAC 0.08 or more?

Answer 4

4 clues

Question 5

Describe the procedure for equal tracking:

Answer 5

1. Position stimulus approx. 12-15 inches from the suspect’s nose and above eye level
2. Move stimulus smoothly from center position to the suspect’s left, then to their right.
3. Movement of the stimulus should take 2 seconds out
4. Make a total of (2) passes

Question 6

Describe the procedure for lack of smooth pursuit:

Answer 6

1. Move the stimulus smoothly from the center to the right (checking their right eye)
2. Movement of stimulus should take approx. two seconds
3. Back across to the left (checking their left eye)
4. Move of stimulus should take approx. two seconds
5. Make two (2) passes
6. Maximum number of clues for lack of smooth pursuit: Two (2). One for each eye

Question 7

Describe the procedure for Distinct and Sustained Nystagmus at Maximum Deviation:

Answer 7

1. Position stimulus about 12-15 inches in front of suspect’s face and slightly higher than their eye level
2. Move stimulus to the right and hold steady for a minimum of 4 seconds
   (observe for distinct and sustained nystagmus)
3. Move stimulus to the left and hold steady for a minimum of 4 seconds
   (observe for distinct and sustained nystagmus)
4. Make (2) passes
5. Maximum number of clues: Two (2). One for each eye.

Question 8

Describe the procedure for Onset of Nystagmus to 45 degrees:

Answer 8

1. Position stimulus about 12-15 in. in front of the suspect’s face
2. Move stimulus slowly towards the right at the speed that would take 4 seconds
3. Once cue is observed, pause and note that it occurred to 45 degrees.
4. Return stimulus to the center of the suspect’s face
5. Move stimulus towards the left at the speed that would take 4 seconds
6. Once cue is observed, pause and note that it occurred to 45 degrees.