The eyes have it

At the side of the road, law enforcement routinely makes DUI arrests based upon results of a Horizontal Gaze Nystagmus (HGN) test. The underlying premise of the test is: you drink enough alcohol, and then you eyes will show HGN.

Alcohol, however, is not the sole cause of HGN. In State v. Horn, the court recognized the following causes or possible causes of HGN:

  • problems with the inner ear labyrinth;
  • irrigating the ears with warm or cold water;
  • influenza; streptococcus infection;
  • vertigo;
  • measles;
  • syphilis;
  • arteriosclerosis;
  • Korchaff's syndrome;
  • brain hemorrhage;
  • epilepsy;
  • hypertension;
  • motion sickness;
  • sunstroke;
  • eye strain;
  • eye muscle fatigue;
  • glaucoma;
  • changes in atmospheric pressure;
  • consumption of excessive amounts of caffeine;
  • excessive exposure to nicotine; aspirin;
  • circadian rhythms;
  • acute head trauma;
  • chronic head trauma;
  • some prescription drugs; tranquilizers,
  • pain medication,
  • anti-convulsant medicine;
  • barbiturates;
  • disorders of the vestibular apparatus and brain stem;
  • cerebellum dysfunction;
  • heredity;
  • diet;
  • toxins;
  • exposure to solvents;
  • extreme chilling;
  • eye muscle imbalance;
  • lesions;
  • continuous movement of the visual field past the eyes; and
  • antihistamine use.