The trigeminal pupillary reflex as a model of vegetative-nociceptive interaction: physiological and clinical aspects.

The study of pupil response to stimuli applied at the corneal level is particularly interesting for the study of integrative sensory-vegetative functions in both physiological and clinical research. In the present study we tried to evaluate and describe pupil response to quantified corneal stimuli in 7 healthy subjects by means of a binocular TV pupillometric device. The pupil response to corneal stimuli was bilateral, direct and consensual. It was characterized by a biphasic progression with an initial response in mydriasis and a later miotic component which was smaller, slower and of longer duration. A direct correlation was observed between the intensity of the stimulus applied and the extent of the mydriasis and between the intensity of the stimulus at the corneal level and the length of the mydriatic response.