Okay, let's tackle this question. The user provided a question about a drug that causes ocular hypotension and apnea in an infant. The correct answer was left blank, so I need to figure out which drug fits that description.

First, I should recall drugs that lower intraocular pressure (IOP). Common ones include beta-blockers, alpha agonists, prostaglandin analogs, and carbonic anhydrase inhibitors. But the key here is that it also causes apnea in infants. That's a red flag for me. I remember that some beta-agonists can cause respiratory issues, but wait—apnea is more commonly associated with central nervous system depressants.

Wait, maybe it's a miotic agent? Like pilocarpine? No, pilocarpine is a cholinergic agonist and can cause miosis, but not sure about apnea. Another thought: epinephrine? No, that's a sympathomimetic and would increase heart rate, not cause apnea.

Oh! Wait, there's a class of drugs called carbonic anhydrase inhibitors. For example, acetazolamide. But acetazolamide can cause respiratory alkalosis, but apnea in infants? Not sure. Another angle: maybe it's related to systemic absorption. For example, topical beta-blockers like timolol. If an infant is exposed, say through a mother's eye drops, could that cause apnea? Yes! Beta-blockers can cross into breast milk or be absorbed systemically, leading to respiratory depression in infants. So timolol is a beta-blocker used for glaucoma (ocular hypotension), and systemic absorption can cause apnea in infants.

So the correct answer is timolol. The other options would be incorrect because, for example, latanoprost is a prostaglandin analog, which doesn't cause apnea. Brimonidine is an alpha-2 agonist, but I'm not sure about apnea. Ketorolac is a NSAID used in eye drops, but again, not associated with apnea in infants. So the key here is beta-blockers causing both ocular hypotension and apnea in infants.

**Core Concept**
Beta-blockers like timolol are used for ocular hypotension in glaucoma. Systemic absorption can cause **bronchoconstriction** and **central respiratory depression**, particularly in infants due to their immature metabolism and lower body weight.

**Why the Correct Answer is Right**
Timolol, a non-selective beta-blocker, reduces intraocular pressure by decreasing aqueous humor production. In infants, systemic absorption via ocular routes can inhibit **β2-adrenergic receptors** in the respiratory center, leading to **apnea**. This risk is heightened in neonates due to poor hepatic metabolism and delayed clearance.

**Why Each Wrong Option is Incorrect**
**Option A:** Latanoprost (prostaglandin analog) lowers IOP but does not cause apnea.
**Option B:** Brimonidine (alpha-2 agonist) reduces IOP and may cause sedation but not apnea.
**Option C:** Acetazolamide (carbonic anhydrase inhibitor) is systemic, not topical, and causes metabolic acidosis, not apnea.

**Clinical Pearl /

✓ Correct Answer: B. Brimonidine