Atropine eye drops are used to temporarily paralyze the accommodation reflex and as a long-lasting pupil dilating agent, or mydriatic. What action causes the dilation effect?

The block of acetylcholine's action.

Explanation:

Atropine is an anticholinergic drug used to treat certain eye conditions and for eye examinations. It acts blocking the action of acetylcholine, this results in myadriasis (dilation of the pupil) due to the relaxation of the sphincter muscle of the iris.

I hope you find this information useful and interesting! Good luck!