Lateralization of Pupillary Light Reflex Parameters

The aim of this study was to determine differing reactions of the left and right eyes with regard to pupillary light reflex (PLR) parameters. All together 90 healthy subjects were included. In the first test series, 34 subjects were investigated on both eyes (left eye was tested first, three tests per day and one reliability test). In the second test series, 32 subjects were studied while changing the beginning side. In the last test series, 29 subjects were investigated 12 times each within one hour (beginning side changed/switched/alternated, without spoken advice/instruction). Infrared pupillometry was used to study pupil diameter, latency time, relative amplitude, contraction/dilation velocity, and pupil redilation time. The study demonstrated significant differences of PLR parameters between both eyes. In contrast to the pupil diameter of the left eye the parasympathetically-dominated right eye was not influenced by vocal instructions and by changing the beginning side. PLR parameters might indicate functional lateralization of autonomic function in the central nervous system. High sensitivity of the procedure (arousal, time of day) is advantageous for various psychophysiological investigations.