The goal of this clinical study is to learn about the short-term physiological effects of low-dose atropine in healthy volunteers. The study seeks to examine three questions related to low-dose topically applied ophthalmic atropine:
1. Does applying two drops of 0.01% atropine sulfate solution cause the same clinical effects as one drop of 0.02% atropine?
2. How quickly do the pupil responses and accommodative amplitudes recover following a dose of 0.01% atropine, 0.02% atropine, and 0.05% atropine?
3. Does applying a single drop of 0.02% atropine sulfate solution cause the same clinical effects in participants with light vs. dark iris colors? Participants will have their pupil size and accommodative status measured at appropriate intervals to answer the questions above.