I mentioned in the previous post that few officers understand the nystagmus test, administer it correctly, or score it objectively. Further problems with using the nystagmus test in DUI investigations have been summarized by a noted expert in the area, Dr. L. F. Dell’Osso, Professor of Neurology at Case Western Reserve University School of Medicine and Director of the Ocular Motor Neurophysiology Laboratory at the Veteran’s Administration Medical Center in Cleveland:

Using nystagmus as an indicator of alcohol intoxication is an unfortunate choice, since many normal individuals have physiologic end-point nystagmus…Without a neuro-opthalmologist or someone knowledgeable about sophisticated methods of eye movement recordings, it is difficult to determine whether the nystagmus is pathologic. It is unreasonable that such difficult judgments have been placed in the hands of minimally trained officers. Dell’Osso, "Nystagmus, Saccadic Intrusions, Oscillations and Oscillopsia", 147 Current Neuro-Opthalmology 147.

See also an interesting article by Umeda and Sakata entitled "Alcohol and the Oculomotor System", 87 Annals of Otology Rhinology 69, wherein scientists concluded that gaze nystagmus was one of the least sensitive eye measurements of alcohol intoxication. The nystagmus which officers are trained to believe indicates intoxication is naturally present in some individuals without the presence of alcohol. It can also be caused by many other factors, as the Supreme Court of Kansas has noted after a review of the scientific literature:

Nystagmus can be caused by problems in an individual’s inner ear…. Physiological problems such as certain kinds of diseases can result in gaze nystagmus….Furthermore, conditions such as hypertension, motion sickness, sunstroke, eyestrain, eye muscle fatigue, glaucoma, and changes in atmospheric pressure may result in nystagmus. The consumption of common substances such as caffeine, nicotine, or aspirin also lead to nystagmus almost identical to that caused by alcohol consumption. State v. Witte, 836 P.2d 1110.

Obviously, drinking coffee and smoking cigarettes are not unusual. And note that most DUI arrests occur late at night — just when eyestrain and eye muscle fatigue are most expected. More on nystagmus to come….