Assessment of pupillary responses to light with IRIS

With a newly developed method, IRIS, the potential usefulness of various parameters of pupillary reflexes for the assessment of autonomic nerve function was studied. Constriction latency decreased and dilatation latency increased significantly with higher intensities of light (P < 0.01 and P < 0.05, respectively). Thirteen subjects were tested twice one year apart in order to examine long-term intra-individual variability; no significant differences (all P > 0.3) were found. Reproducibility and reliability of hippus and pupil cycle time were lower than for the determination of constriction and dilatation latency. None of the parameters was correlated with age (all P > 0.3). We conclude that pupillary constriction and dilatation latency, assessed with IRIS, are the main dynamical parameters for the study of parasympathetic and sympathetic parts of the autonomic nervous system, that controls the pupillary system. Although a statical parameter, useful additional information may be obtained from the dark adapted pupil diameter. Hippus cycle time and pupil cycle time do not provide additional information and therefore cannot be recommended as standard tests for autonomic nerve function.