SFST Clues
HGN — Horizontal Gaze Nystagmus
Max 6 clues4 or more clues = likely BAC ≥ 0.08
1.Lack of smooth pursuit — Left eye
2.Lack of smooth pursuit — Right eye
3.Distinct and sustained nystagmus at maximum deviation — Left eye
4.Distinct and sustained nystagmus at maximum deviation — Right eye
5.Onset of nystagmus prior to 45 degrees — Left eye
6.Onset of nystagmus prior to 45 degrees — Right eye
Note: Check for equal pupil size, resting nystagmus, and equal tracking. Medical conditions and certain medications can cause nystagmus.
Walk and Turn
Max 8 clues2 or more clues = likely BAC ≥ 0.08
1.Cannot keep balance during instructions
2.Starts too soon
3.Stops while walking
4.Does not touch heel-to-toe
5.Steps off the line
6.Uses arms to balance (6+ inches)
7.Improper turn
8.Incorrect number of steps
Note: 9 heel-to-toe steps, turn, 9 heel-to-toe steps back. Must be performed on a reasonably dry, hard, level, non-slippery surface.
One Leg Stand
Max 4 clues2 or more clues = likely BAC ≥ 0.08
1.Sways while balancing
2.Uses arms to balance (6+ inches)
3.Hopping
4.Puts foot down
Note: Subject raises one foot approximately 6 inches off the ground and counts "one thousand one, one thousand two..." for 30 seconds. Time the test.