Electronic pupillometry for investigating pupil reactivity to different exteroceptive stimuli: applications and limits.

Iris neuromuscular junction represents a site of reciprocal interactions of sympathetic and parasympathetic innervation and can be considered a useful tool to investigate both systems in physiological and pathological conditions. In this study 35 healthy subjects of different ages were examined by an infrared TV pupillometer to assess darkness and light adaptation, as well as pupillary response to light and to exteroceptive stimulation (RIII reflex). A progressive impairment of pupil adaptability to light stimuli with aging was also observed, while a significant correlation was found between the intensity of electrical stimulation of the sural nerve and the percent increase in pupil diameter. The evaluation of pupil responsiveness is considered for its possible applications in various neurological disorders.