[Age effects of topical tyramine and cocaine on the pupil]

In order to obtain the age distribution of normal values of the effects of topical tyramine or cocaine on the pupil, we measured the pupillary light reflexes of 50 normal volunteers before and 45 minutes (tyramine) or 90 minutes (cocaine) after the topical instillation in right eyes. Left eyes were used as controls. An infrared videopupillogram (HTV-C301) was used. Topical tyramine as well as cocaine caused mydriasis, increase of maximum %-velocity of dilatation (%-VDmax), reduction of %-amplitude of constriction (%-A) and decrease of maximum %-velocity of constriction (%-VCmax). These alternations of pupillary parameters coincided with the changes induced by topical epinephrine. The effects of tyramine or cocaine significantly increased as the age of the subjects increased, though the increase of %-VDmax caused by cocaine was only related to age. Age-related augmentation of pupillary changes were also been observed in a previous study using topical epinephrine or topical pilocarpine which concluded that the effects of any topical autonomics were increased by aging. No physiological senile Horner's syndrome was detected. It was concluded that the age-related augmentation of pupillary changes caused by topical autonomics probably resulted from the increment of corneal permeability in the aged which was confirmed in the previous fluorophotometric study by the authors following topical fluorescein administration. It is possible to assess the pupillary sensitivity to topical adrenergics of the patients with bilateral Horner's syndrome by comparing the age-related normal values obtained in this study.