Pupil function as a parameter for assessing impairment of the central nervous system from a traffic-medicine perspective

Abstract To evaluate an individuals driving safety objective measurement methods are required which allow reproducible, reliable and subsequently verifiable data to be collected. In this study, we exposed healthy test subjects ( n = 41), as well as persons who were under the influence of drugs and/or medication ( n = 105), to different light stimuli and tested the pupillary light reflex in order to gain a better understanding of the physiological and pathological pupil function. The tests were performed using a “Compact Integrated Pupillograph” (CIP), which enables pupil reactions to be measured using infrared technology. The primary aim was to assess the applicability and value of infrared pupillography as an objective measurement method for assessing persons with impairments of the central nervous system in terms of their driving safety and fitness to drive. There were highly significant differences for almost all the evaluated parameters between the groups tested. In particular, the synoptic examination of numerous parameters measured by this system, and the possibility of examination under various conditions, especially in terms of light stimuli intensity, made it possible to achieve highly significant differentiation between persons with impairments of the central nervous system and control persons. On the basis of the results obtained, it can be categorically stated that infrared pupillography represents an objective method of measuring pupil function. In order to increase legal certainty it would thus appear desirable to make infrared pupillography a routine part of police checks.