A Pupillographic Evaluation of a Phenylephrine HC1 5% - Tropicamide 0.8% Combination Mydriatic

A continuously recording high-resolution pupillometer was used to measure changes in pupil size and pupil reactivity to temporally modulated light, following topical application of a phenylephrine HCl 5%-tropicamide 0.8% combination mydriatic (Phenyltrope). A controlled light stimulus induced pupillary changes in the left eye while changes in the consensual pupillary responses were measured in the mydriatic-treated right eye. The effects on pupil light reactivity of a single drop of the combination mydriatic were also compared to those caused by one drop of tropicamide 1% alone. Phenyltrope was introduced onto the ophthalmic market ostensibly offering faster mydriasis because of its combined effect of both the parasympathetic and sympathetic innervation to the pupil. In the present study, we looked for any differences in the pupil reaction times and amplitudes as a function of time after drug administration, iris coloration and type of mydriatic instilled. Our results show that while the combination is a fast acting mydriatic providing a large and stable pupillary dilation in subjects with either blue or brown irides, it does not differ appreciably in efficacy from the mydriatic effect of tropicamide 1% alone in healthy subjects between 20 to 36 years of age. Applications of our findings to the clinical environment are presented.