At what angle is the onset of nystagmus evaluated during the HGN test?

At what angle is the onset of nystagmus evaluated during the HGN test?

• A. 30 degrees
• B. 45 degrees
• C. 60 degrees
• D. 90 degrees

Answer: (B)

The onset of nystagmus during the Horizontal Gaze Nystagmus (HGN) test is evaluated at an angle of 45 degrees. This specific angle is significant because it allows the examiner to observe the involuntary eye movements that indicate possible impairment due to alcohol or other substances. At 45 degrees, the eyes are in a position where the nystagmus, which is characterized by a jerking or oscillatory movement, can be most readily detected, making it a reliable and standard measure used during field sobriety tests. In addition, the assessment includes monitoring for the smoothness of eye tracking and the presence of nystagmus at both the onset and maximum deviation. Evaluating nystagmus at 45 degrees ensures consistency and accuracy in detecting signs of impairment based on the physiological responses of the individual being tested.

The onset of nystagmus during the Horizontal Gaze Nystagmus (HGN) test is evaluated at an angle of 45 degrees. This specific angle is significant because it allows the examiner to observe the involuntary eye movements that indicate possible impairment due to alcohol or other substances. At 45 degrees, the eyes are in a position where the nystagmus, which is characterized by a jerking or oscillatory movement, can be most readily detected, making it a reliable and standard measure used during field sobriety tests.

In addition, the assessment includes monitoring for the smoothness of eye tracking and the presence of nystagmus at both the onset and maximum deviation. Evaluating nystagmus at 45 degrees ensures consistency and accuracy in detecting signs of impairment based on the physiological responses of the individual being tested.