Oculomotor Signs

For more than a century (Diefendorf & Dodge, 1908), researchers from the domains of psychology, physiology, neurology, and psychiatry have worked to compile an extensive catalogue of oculomotor signs of neural impairment, injury, and disease.  Using the known range of normal human eye-movements (e.g., Schalen, 1980; Bahill, Brockenbrough, & Troost, 1981) on standard tasks (e.g., Antoniades et al., 2013; Liston & Stone, 2014), neuroFit seeks to understand the factors that may degrade performance, including impairments like fatigue or alcohol intoxication, brain injury, or the presence of disease.  

Grossly-observable oculomotor signs have been incorporated into field tests that support quick decisions about an individual’s state of neural health.  One well-known example occurs in the field sobriety test: a police officer stands opposite the subject and asks the subject to keep his or her head straight forward while maintaining steady fixation on the officer’s finger first at a central position, then at a very peripheral position.  In intoxicated individuals (Aschan, 1958), fixation of a very peripheral target can become unsteady; the eye slips off target then quickly jerks back onto the target, an oculomotor sign called nystagmus.    

In some disease states (e.g., traumatic brain injury, schizophrenia, Parkinson’s disease), characteristic oculomotor signs can occur.  For example, square-wave jerk describes an oculomotor sign in which steady fixation is interrupted by paired sets of small horizontal saccades within a short interval.  These occur in several neurodegenerative conditions, including progressive supranuclear palsy, Huntington’s disease, Parkinson’s disease, Friedreich’s ataxia, and multiple system atrophy, but have also been reported to occur in anorexia nervosa, aged populations, and can sometimes occur in subjects without any type of neurological or psychiatric condition.  In neurodegenerative conditions, square-wave jerk is often accompanied by other oculomotor signs such as prolonged movement latency, low-gain pursuit, and an inability to suppress reflexive saccades (Anderson & MacAskill, 2013).  neuroFit uses a patented technique developed by NASA to derive a set of oculomotor signs for any factor known to degrade performance, including brain injury or disease.  

neuroFit ONE (Oculometric Neurological Examination™) allows the performance of an individual to be measured and monitored over time to understand day-to-day factors that may degrade performance … and ultimately the factors that contribute to optimal neural health.

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