**Core Concept**
Decreasing aqueous humor formation is a therapeutic strategy for managing glaucoma. The aqueous humor is produced in the ciliary body and flows through the trabecular meshwork to exit the eye, maintaining intraocular pressure (IOP). Reducing aqueous production can lower IOP, alleviating glaucomatous damage.

**Why the Correct Answer is Right**
The correct answer is the one that does not decrease aqueous humor formation. Some medications, like beta-blockers, prostaglandin analogs, and alpha-2 agonists, decrease aqueous humor production by affecting the ciliary epithelium. This can be achieved through various mechanisms:
- Beta-blockers inhibit the beta-adrenergic receptors, reducing cyclic AMP levels and subsequent aqueous production.
- Prostaglandin analogs increase uveoscleral outflow, but some also decrease aqueous production by affecting the ciliary epithelium.
- Alpha-2 agonists, such as brimonidine, decrease aqueous production by reducing the release of neurotransmitters that stimulate aqueous production.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because beta-blockers do decrease aqueous humor formation by inhibiting beta-adrenergic receptors.
**Option B:** This option is incorrect because prostaglandin analogs, while primarily increasing uveoscleral outflow, can also decrease aqueous production.
**Option C:** This option is incorrect because alpha-2 agonists, such as brimonidine, decrease aqueous humor formation by reducing neurotransmitter release.

**Clinical Pearl / High-Yield Fact**
When treating glaucoma, it's essential to understand the mechanism of action of each medication to choose the most effective treatment for each patient. A combination of medications that decrease aqueous production and increase outflow may be necessary to achieve optimal IOP control.

**Correct Answer: D.**