Survey on DUI cases - HGN

Horizontal Gaze Nystagmus

Horizontal Gaze Nystagmus (HGN) is an eye exam. Nystagmus is an involuntary contraction of the eyes than when the eyes of the central position is defined on the side. Alcohol and some drugs cause HGN. If administered properly, is 77% HGN critical for the person with a blood alcohol count (BAC) of 0.10%.

To obtain the precise result, HGN must be implemented properly. To exclude that HGN is causedfrom a medical condition, have the subject's eyes can be observed in a resting position. The officer must follow the theme, with both official and subject to a stop. The eyes should be checked only by the size of the pupil of a tie, resting nystagmus, and monitoring of equality. Equal-tracking refers to the ability of the eyes on an object to follow along. If students are significantly unequal in size, or if the eyes do not track together, there is the possibility that the nystagmus is caused by injury ormedical condition.

Having established that there were no injuries or illness, the officer will begin the HGN test. The officer and the subject should be at the same time and are facing each other. If the subject wears glasses should remove the topic. The officer must issue clear instructions. These indications are:

First "I'll check your eyes'

According to "Keep your head still and follow this stimulus with your eyes only"

Third 'Continue to followstimulus with the eyes until I say stop "

The appeal that the counselor can use a pencil, pen, lean or flashlight, called Penlight. The action must be taken 12-15 cm from the nose of the subject and kept slightly above eye level. There are three different "tests" that the officer is looking for.

A clue: Lack of Smooth Pursuit

The attraction begins in the center, then there is the issue moves to the left, with regard to the subject's eyes can movePage so that no white is showing in a corner of the eye. This position is for 2 seconds and then kept the suggestion on the law as far as the eye can go to the presentation page. This position is pressed for 2 seconds. This process is then repeated. The officer is considering if your eyes gently, or when moving or tearing rebound. One example of eye movement is smooth as a marble moves on a glass plate. An example of a tear or rebound is aMarble in motion a piece of sandpaper, they do not move in a straight line.

Two Clue: significant and sustained nystagmus at maximum deviation

The appeal will start in central location and then move the issue is regarding the subject may be in the left eye. This position is held for 4 seconds and then the suggestion on the law regarding the subject's eyes, go to this page and put in place by 4 seconds. This process is then repeated. TheOfficer is to look at, when the eye is clear and sustained contractions, when the eye at maximum deviation (out) is.

Clue Three: Onset of Nystagmus Prior to 45 degrees

The attraction begins in the center and then the topic shifted to the left edge of the subject on his shoulders and held for 4 seconds. This is then repeated to the subject of law. This process is then repeated. The officer is looking for a strong contraction. If the officer seesConvulsions, the officer should keep the stimulus position and confirm that the judder is present. To determine that indeed is the appeal of 45 degrees just before a great amount of skill and practice is positioned at the police.

The official determination of all the instructions in each phase, both the right and left eye closed. If the officer deems that the evidence showed about 4 or more during the HGN test, there is a 77%Probability that the subject has a BAC above 0.10%.

Caution

If the officer keeps his eyes on the problem of maximum deviation of more than 30 seconds, the subject will reflect tired eyes and nystagmus. This is called nystagmus fatigue.

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