Pupil function as an indicator for being under the influence of central nervous system-acting substances from a traffic-medicine perspective

To evaluate an individual's ability to drive safely, objective measurement methods are required. The primary aim of this study was to assess the applicability and value of infrared pupillography as an objective measurement method to indicate possible influence of central nervous system-acting substances. 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 using infrared technology. The synoptic examination of numerous parameters, and the possibility of examination under various conditions, made it possible to achieve highly significant differentiation between persons who were under the influence of drugs and/or medication and control persons. Infrared pupillography represents an objective method of measuring pupil function, providing a reliable indicator of previous consumption of drugs and/or medication. In order to increase legal certainty it would thus appear desirable to make infrared pupillography a routine part of police checks in the near future.