Nystagmus Awareness Day & DWI

Recognizing How Nystagmus Impacts Your DWI Charge

June 20th is Nystagmus Awareness Day, and while this may seem irrelevant to those who don’t have nystagmus, we urge you to think again. Your DWI charge could easily stem from failing the horizontal gaze nystagmus (HGN) test, which is a part of the Standardized Field Sobriety Test (SFST) battery. While the HGN test is only 77% accurate, it sheds awareness on the fact that failing the HGN test could result from underlying medical conditions such as nystagmus as well as external conditions.

What Is Nystagmus?

Nystagmus is “ … a vision condition in which the eyes make repetitive, uncontrolled movements. These movements often result in reduced vision and depth perception and can affect balance and coordination,” according to the American Optometric Association. It further describes what causes nystagmus:

  • Lack of development of normal eye movement control early in life
  • Very high refractive error, for example, nearsightedness (myopia) or astigmatism
  • Congenital cataracts
  • Inflammation of the inner ear
  • Medications such as anti-epilepsy drugs
  • Central nervous system diseases
    • Alcohol and certain drugs also depress the central nervous system

Horizontal Gaze Nystagmus Test

The HGN test measures involuntary eyeball jerking that occurs as eyes gaze side-to-side horizontally. An officer may issue this SFST if they suspect you are driving while intoxicated, regardless of whether external factors or underlying medical conditions may interfere.

First, they will have you safely exit your vehicle and direct you to a designated spot to take the test. Then, they may instruct you to follow the direction of their pen, pencil or penlight with your eyes. During this process, they will move the object horizontally and monitor your eye movement. They will look for three elements that signal impairment:

  • Lack of smooth pursuit
  • Distinct and sustained nystagmus at maximum deviation
  • Onset of nystagmus prior to 45 degrees

If you have nystagmus and are unable to perform the HGN test successfully, you may get a DWI charge. Even if you don’t have this condition but other factors besides alcohol and drugs affected your nystagmus, you may face this serious accusation even though it’s not your fault. Law enforcement may not consider whether your nystagmus or other uncontrollable factors impacted your test results, and frankly, they may not care.

Regardless of what leads to your DWI charge, our Fort Worth defense lawyer is prepared to fight against your accusation. We obtain 35+ years of combined experience protecting the rights and freedoms of the accused and will gladly help you fight for a favorable outcome in your DWI case. Don’t hesitate to reach out to us at (817) 435-4970 for a free consultation to learn how our DWI attorney can help you!


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