Clinical quantitative pupillometry: The latency of pupillary constriction as measured with the IRIS system (preliminary results)

Using the IRIS pupillometer described by Reulen et at. (1988), a group of 46 patients suffering from optic neuritis was investigated. The latency of the pupil constriction was determined and shown to be prolonged when the affected eye was stimulated with visible light, prolonged with respect to stimulation of the healthy fellow eye. In a small group of nine myotonic dystrophy patients also the latency of the peak constriction was measured. In the latter group only the interval between onset of constriction and peak velocity was prolonged. This interval could not be proven to be prolonged in the group of optic neuritis patients. This may indicate that the constriction latency is a reliable parameter for detecting nervous dysfunction, while the difference between moment of onset and peak velocity can be used to determine muscle dysfunction.