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

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.

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.

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).

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.