Which of the following drug produce analogous action on dilator pupillae as is produced by pilocarpine on sphincter pupillae?
**Core Concept**
The question is testing the understanding of the autonomic innervation of the iris, specifically the muscarinic receptors on the sphincter pupillae and the adrenergic receptors on the dilator pupillae. Pilocarpine, a muscarinic agonist, causes miosis by stimulating the sphincter pupillae.
**Why the Correct Answer is Right**
The correct answer is a muscarinic antagonist, which has an analogous action on the dilator pupillae as pilocarpine on the sphincter pupillae. This is because the dilator pupillae is innervated by the sympathetic nervous system, which uses adrenergic receptors. A muscarinic antagonist can block the parasympathetic stimulation of the sphincter pupillae, allowing the sympathetic stimulation of the dilator pupillae to dominate, resulting in mydriasis. The correct answer is atropine, which is a muscarinic antagonist that can block the parasympathetic stimulation of the sphincter pupillae.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is not provided.
* **Option B:** This option is not provided.
* **Option C:** This option is not provided.
* **Option D:** This option is not provided.
**Clinical Pearl / High-Yield Fact**
Atropine can cause mydriasis and cycloplegia by blocking the parasympathetic stimulation of the sphincter pupillae and the ciliary muscles, respectively. This makes it a useful medication for diagnostic purposes, such as dilating the pupils for retinoscopy.
**Correct Answer:** A. Atropine.