Effects of mydriatics on rod/cone- and melanopsin-driven pupil responses

TY - JOUR

T1 - Effects of mydriatics on rod/cone- and melanopsin-driven pupil responses

AU - Flanagan, Sarah

AU - Saunders, Kathryn J

AU - Queener, Hope

AU - Richardson, Patrick

AU - Ostrin, Lisa

PY - 2019/12/17

Y1 - 2019/12/17

N2 - Significance: Pupillometry protocols evaluating rod/cone- and melanopsin-driven responses often utilize 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: To compare effects of atropine, a muscarinic antagonist, and phenylephrine, an adrenergic agonist, on consensual pupil responses, and to assess repeatability of pupil metrics without mydriasis. Methods: Right eye pupil responses of 20 adults, aged 21-42, 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 (s) 651 nm “red” and 456 nm “blue” flashes. Metrics included baseline pupil diameter, maximum constriction, 6 s and 30 s post illumination pupil responses, and early (0-10 s) and late (10-30 s) areas under the curve. Results: Dilation of the stimulated eye with either mydriatic significantly increased the 6 second post illumination 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 s 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). Conclusion: 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.

AB - Significance: Pupillometry protocols evaluating rod/cone- and melanopsin-driven responses often utilize 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: To compare effects of atropine, a muscarinic antagonist, and phenylephrine, an adrenergic agonist, on consensual pupil responses, and to assess repeatability of pupil metrics without mydriasis. Methods: Right eye pupil responses of 20 adults, aged 21-42, 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 (s) 651 nm “red” and 456 nm “blue” flashes. Metrics included baseline pupil diameter, maximum constriction, 6 s and 30 s post illumination pupil responses, and early (0-10 s) and late (10-30 s) areas under the curve. Results: Dilation of the stimulated eye with either mydriatic significantly increased the 6 second post illumination 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 s 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). Conclusion: 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.

KW - intrinsically photosensitive retinal ganglion cells

KW - melanopsin

KW - mydriatics

KW - pupil responses

KW - atropine

KW - phenylephrine

KW - post-illumination pupil response

M3 - Article

JO - Optometry and Vision Science

JF - Optometry and Vision Science

SN - 1040-5488

ER -