Pulled over by the police in Texas for suspicion of driving while intoxicated? The police will attempt to make you perform a series of tests. Generally, there are three tests that police officers have a driver perform to help them establish intoxication. One of those tests is called the Horizontal Gaze Nystagmus. 

Before we go any further, know that it is our advice that you do not perform any field sobriety test.  These tests are not in place to help you establish that you are sober.  They perform the tests to give them grounds to arrest you for DWI.  Stay polite, give them your driver’s license and refuse to answer any further questions.

Horizontal Gaze Nystagmus

Now, on to the Horizontal Gaze Nystagmus.  The brain controls eye movement. Your eyes move automatically to adjust when you move your head slightly. This stabilizes the image that you are looking at so you see a sharper image. In people with nystagmus, the areas of the brain that controls eye movements do not work properly.  When you are intoxicated, this is one of the abilities that may be compromised.


To perform this test, the officer should place you in a well-lit area.  If it is a dark area, they may use a flashlight.  However, the flashlight or the headlights from passing vehicles could skew the results.

The officer should tell you that they are going to check your eyes. They should ask if you are wearing contacts or have any medical issues which could affect the results. 

The officer will then ask you to follow an object. Usually the tip of a pen or pen light, placed 12 to 15 inches away, with only your eyes.  The officer will look for the following three results:

  1. Lack of Smooth Pursuit. Does your eye follow the object smoothly as it moves from the center of your face toward the ear? Or, does it jerk?
  2. Distinct Nystagmus at Maximum Deviation. Does your eye have a distinct jerking motion after being held toward the outer edge for four seconds?
  3. Onset of Nystagmus Prior to 45 Degrees.  As the officer moves the object towards the edge of your shoulder, does your eye jerk before the object is 45 degrees from the center of your face?

Other Factors

Most officers will not tell you what types of medical issues could affect the results.  Medical issues could affect nystagmus. These include head injuries, inner ear problems, multiple sclerosis, diabetes, certain medications such as lithium or anti-seizure medications, a wide number of eye problems or even a family history of nystagmus.

In addition to the medical issues, there are additional causes of nystagmus. They include water in your ear, taking a decongestant, flashing light in one eye, nicotine or even vibrations.


As you can see, there is no good reason to allow a police officer to give you a Horizontal Gaze Nystagmus test.  Remember to always be polite and respectful.  But, do not give them any information without your attorney present. Only provide your name, driver’s license and proof of insurance.

the ultimate servival guide for texas injured