<prompt> Which is the shoest acting mydriatic?TropicamideAtropinePhenylephrineHyoscine  <response>: Tropicamide is the quickest 20-40min and shoest acting 3-6hours mydriatic. Atropine is a potent mydriatic but its slow and has long lasting action. With it, pupil dilates in 30-40min but cycloplegia takes 1-3hours. 