**Core Concept**
Iris cysts, also known as iris pearls or iris nodules, are small, round, fluid-filled lesions that can form on the iris, often associated with chronic inflammation or trauma. They are typically benign but can cause visual disturbances.

**Why the Correct Answer is Right**
The formation of iris cysts is thought to be related to the accumulation of fluid within the iris stroma, which can occur due to chronic inflammation or trauma. The use of certain medications, such as corticosteroids, can help reduce inflammation and prevent the formation of iris cysts. Specifically, **cycloplegic agents** like atropine or homatropine can help prevent the formation of iris cysts by reducing the amount of fluid within the iris stroma.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because the use of miotics, such as pilocarpine, can actually increase the risk of iris cyst formation by increasing the amount of fluid within the iris stroma.
**Option B:** This option is incorrect because the use of anticholinergics, such as atropine, is actually a treatment for iris cysts, not a preventive measure.
**Option C:** This option is incorrect because the use of alpha-2 agonists, such as brimonidine, is not typically associated with the prevention of iris cysts.

**Clinical Pearl / High-Yield Fact**
When managing patients with iris cysts, it's essential to consider the use of cycloplegic agents, such as atropine or homatropine, to reduce inflammation and prevent further cyst formation.

**Correct Answer:** D. Cycloplegic agents.