In this double-masked clinical study, we evaluated four concentrations of tropicamide (0.05%, 0.1%, 0.25%, and 0.5%) combined with hydroxyamphetamine 1% to find the combination that gives maximal pupillary dilation and inhibition of responsiveness to light and minimal paralysis of accommodation. With all concentrations, pupil size was maximal at 60 minutes, and there was no significant difference between the groups in mean pupillary diameter. Inhibition of the pupillary responses to light and loss of accommodation were directly related to the concentration of tropicamide. Tropicamide 0.25% combined with hydroxyamphetamine 1% was considered ideal for dilation and inhibition of the light response without inhibiting accommodation for near vision.