**Core Concept**
Reverse hypopyon refers to the settling of red blood cells in the anterior chamber of the eye, opposite to the usual settling of leukocytes in hypopyon. This phenomenon occurs due to the increased pressure in the anterior chamber forcing the red blood cells to settle in the anterior chamber.

**Why the Correct Answer is Right**
Reverse hypopyon is typically seen in conditions with increased intraocular pressure, such as angle-closure glaucoma. The increased pressure pushes the red blood cells from the vitreous humor into the anterior chamber, where they settle due to gravity. This can be a sign of severe ocular disease and requires urgent medical attention.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because reverse hypopyon is not typically associated with conditions that cause decreased intraocular pressure.
**Option B:** This option is incorrect because while hypopyon can be a sign of uveitis, reverse hypopyon is not typically seen in this condition.
**Option C:** This option is incorrect because reverse hypopyon is not a characteristic feature of retinal detachment.

**Clinical Pearl / High-Yield Fact**
In cases of reverse hypopyon, it is essential to consider the possibility of angle-closure glaucoma and to perform a thorough ocular examination, including measurement of intraocular pressure.

**Correct Answer: A. Reverse hypopyon in angle-closure glaucoma.**