## **Core Concept**
Brimonidine is an alpha-2 adrenergic agonist used in the treatment of glaucoma. Its primary mechanism of action involves decreasing intraocular pressure (IOP), which is crucial in managing glaucoma. The drug achieves this by reducing aqueous humor production and increasing uveoscleral outflow.

## **Why the Correct Answer is Right**
The correct answer, **D. Decrease aqueous humor production and increase uveoscleral outflow**, is accurate because brimonidine acts on alpha-2 adrenergic receptors in the eye. By stimulating these receptors, brimonidine decreases the production of aqueous humor in the ciliary body and increases the uveoscleral outflow of aqueous humor. This dual action effectively lowers intraocular pressure, thereby helping to prevent or slow the progression of glaucomatous damage.

## **Why Each Wrong Option is Incorrect**
- **Option A:** Increasing aqueous humor production would actually worsen glaucoma by increasing intraocular pressure, which is the opposite of the desired therapeutic effect.
- **Option B:** While prostaglandin analogs increase uveoscleral outflow, this is not the mechanism by which brimonidine works. Brimonidine's action is more closely related to its effect on aqueous humor dynamics and alpha-2 adrenergic receptors.
- **Option C:** Decreasing trabecular outflow would also increase intraocular pressure, which is counterproductive in the treatment of glaucoma.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that brimonidine can cause allergic conjunctivitis and should be used with caution, especially in patients with known allergies. Additionally, its use can be associated with cardiovascular and neurological side effects due to its systemic absorption.

## **Correct Answer:** **D.** Decrease aqueous humor production and increase uveoscleral outflow