Résumé : | SIGNIFICANCE: Pupillometry protocols evaluating rod/cone- and melanopsin-driven responses often use mydriatics to ensure maximal stimulus exposure; however, retinal effects of mydriatics are not fully understood. We
demonstrate that dilation with either atropine or phenylephrine results in similar enhancements of rod/cone- and
melanopsin-driven pupil responses.
PURPOSE: The purposes of this study were to compare the effects of atropine, a muscarinic antagonist, and phenylephrine, an adrenergic agonist, on consensual pupil responses and to assess the repeatability of pupil metrics
without mydriasis.
METHODS: Right eye pupil responses of 20 adults aged 21 to 42 years were recorded before and 45 minutes after
instillation of 0.5% atropine or 2.5% phenylephrine in the left eye. Stimuli were presented to the left eye and
included six alternating 1-second 651-nm “red” and 456-nm “blue” flashes. Metrics included baseline pupil
diameter, maximal constriction, 6- and 30-second post-illumination pupil responses, and early (0 to 10 seconds)
and late (10 to 30 seconds) areas under the curve.
RESULTS: Dilation of the stimulated eye with either mydriatic significantly increased the 6-second postillumination pupil response and early and late areas under the curve for blue stimuli, and early area under the curve
for red stimuli (P < .05 for all). Melanopsin-driven post-illumination pupil responses, achieved with either phenylephrine or atropine, did not significantly differ from each other (P > .05 for all). Without mydriasis, intersession
intraclass correlation coefficients for pupil metrics were 0.63 and 0.50 (6- and 30-second post-illumination pupil
responses, respectively) and 0.78 and 0.44 (early and late areas under the curve, respectively) for blue stimuli,
with no significant difference between sessions (P > .05 for all).
CONCLUSIONS: Dilation with phenylephrine or atropine resulted in similar enhancements of the rod/cone- and
melanopsin-driven pupil responses, despite differing mechanisms. Early pupil metrics without mydriasis demonstrated moderate to good intersession repeatability. |