ABSTRACT
Measurements of pupillary diameter, eye tracking, and the pupillary response to a flash of light are readily available, non-invasive indices of central nervous system function. Recently, such parameters have been used by law enforcement personnel, employers, and primary care and emergency room physicians to make a rapid and initial assessment of recent drug ingestion. In this chapter, the physiological basis for the control of pupil size and the light reflex and the instruments used to measure pupillary responses are briefly reviewed. The results of a residential, within-subject study of the effects of various drugs of abuse on pupillary size and the light reflex are described. A summary of the literature on the effects of abused drugs on pupillary measures is given. An outpatient study analyzing the effects of polydrug use on pupillary responses is also presented. The advent of new classes of pupillometers that measure eye position and gaze is also included. These new instruments hold great promise for revealing subjective effects of drugs and drug withdrawal through a psychophysiologic measure. The chapter concludes with a discussion of the utility and limitations of pupillometry in the detection of abused drugs.
