Dose Dependent Effects of Atropine on Static and Dynamic Pupil and Accommodation Metrics in Young Adults.

Purpose: The purpose of this study was to investigate short-term effects of a range of low-dose atropine concentrations on static and dynamic pupil and accommodation metrics in young adults. Methods: This double blinded study tested pupil and accommodation metrics at baseline and 1 hour and 24 hours after topical instillation of a single drop of placebo, 0.01%, 0.025%, 0.05%, and 0.1% atropine in the right eyes of 20 healthy adults (18-35 years). Static pupil diameter was measured under photopic, mesopic, and scotopic illumination, and dynamic responses were recorded as illumination changed from 0.3 to 140 lux using a pupillometer (MYAH). Peak constriction and dilation velocities were extracted. Accommodative lag and maximum accommodation were determined (WAM-5500) and dynamic responses were recorded for targets at 33 cm and 6 m (PowerRef). Dynamic responses were fitted with exponential functions to calculate amplitude, time constant, and peak velocities. Results: Static pupil diameters under all lighting conditions and dynamic metrics, including constriction amplitude and peak constriction and dilation velocities, showed significant dose-response effects at 1 hour and 24 hours (P < 0.05 for all). Maximum accommodation significantly decreased at 1 hour and 24 hours after atropine administration compared to placebo for all concentrations (P < 0.05 for all). Accommodative time constant increased and peak velocity decreased over 24 hours after atropine administration (P < 0.05). On the other hand, accommodative and disaccommodative amplitudes, disaccommodative time constant, and peak velocity did not significantly change after atropine administration (P > 0.05). Conclusions: A single drop of 0.01%, 0.025%, 0.05%, and 0.1% atropine induced significant changes in static and dynamic pupil and accommodation metrics in a dose-dependent manner in young adults.