Which medication is known to cause dilated pupils?

Atropine sulfate eye drops are specifically designed to dilate the pupils, a process known as mydriasis. This medication works as an anticholinergic agent, inhibiting the action of acetylcholine on the longitudinal muscle of the iris and thus preventing pupil constriction. It is commonly used in ophthalmology during eye examinations to provide a better view of the retina and other structures in the eye.

In contrast, while adrenaline (epinephrine) can influence various body responses including pupil dilation due to its sympathomimetic effects, it is not primarily used for this purpose. Fentanyl, an opioid analgesic, generally causes constricted pupils (miosis), and aspirin does not have any direct effect on pupil size. Therefore, atropine sulfate eye drops are the clear answer as they are specifically intended to induce pupil dilation.