What are the three tests that are given in the horizontal gaze nystagmus test?
What are the three tests that are given in the horizontal gaze nystagmus test?
HGN Cues/Clues of Intoxication There are a total of three clues that can be assessed in this test: lack of smooth pursuit, distinct nystagmus at maximum deviation, and the onset of nystagmus prior to 45 degrees. Each eye is scored independently for three clues in each eye giving a total of six indicators/cues.
How many clues are on the horizontal gaze nystagmus test?
six clues
Horizontal Gaze Nystagmus There are six clues, or three in each eye: Lack of smooth pursuit. Distinct and sustained nystagmus at maximum deviation. Onset of nystagmus prior to 45-Degrees.
How accurate is the horizontal gaze nystagmus test?
This test is one of the more accurate field sobriety tests, but it is still only around 77% accurate when determining if a person is impaired — and then only under ideal conditions, not when a subject is on the side of a road, in traffic.
How do you perform the horizontal gaze nystagmus test?
To administer the test, the officer will hold a small object approximately 12-15 inches from your nose and slowly move it from one side to the other. You will follow the object with your eyes while keeping your head still. The officer will look for three different clues in each (for a total of six) during the test.
How do you test for horizontal nystagmus?
Move the object a second time to the 45-degree angle of gaze, taking about four seconds. As the subject’s eye follows the object, watch for it to start jerking. If you think you see distinct nystagmus, stop the movement to see if the jerking continues. If it does, this point is the angle of onset.
What does horizontal nystagmus indicate?
It occurs when there is an irregularity in the inner ear system or a problem affecting the oculomotor control of the eye. A horizontal gaze nystagmus is a lateral or horizontal jerking movement when a person looks toward the side.
What can cause horizontal gaze nystagmus?
Horizontal gaze nystagmus causes-drugs and medicines: Nystagmus may be due to causes other than alcohol in three to four percent of the population. Some of these causes include inner ear fluid movement, seizure medical condition drugs, phencyclidine (PCP), barbiturates and other depressants.
How is nystagmus diagnosed?
Nystagmus is diagnosed by an ophthalmologist. They will examine the inside of your eyes and test your vision. Your ophthalmologist will also look for other eye problems that may be related to nystagmus. These problems could include strabismus (misaligned eyes), cataracts (clouding of the eye’s lens),…
What is the abbreviation for horizontal gaze nystagmus?
HGN is the abbreviation for “horizontal gaze nystagmus,” and is also referred to as the “horizontal gaze nystagmus test.” This evaluation was approved by the National Highway Traffic Safety Administration (NHTSA), in 1984, as a standardized field sobriety test, to be used in driving under the influence cases.
What is Gaze evoked nystagmus?
Gaze-evoked nystagmus is a drift of the eye which is only present for certain directions of gaze. When using EOG recordings, any persistent nystagmus for ocular displacements of 30 degrees or less is considered abnormal.
