**Core Concept**
Acute congestive glaucoma, also known as acute angle-closure glaucoma, is a medical emergency characterized by a sudden increase in intraocular pressure (IOP) due to blockage of the trabecular meshwork. The primary goal of treatment is to reduce IOP and prevent further damage to the optic nerve.

**Why the Correct Answer is Right**
The best prophylaxis for the fellow eye in a patient with acute congestive glaucoma involves identifying and addressing any risk factors that may contribute to angle closure. This includes assessing the anterior chamber depth, using gonioscopy to evaluate the angle, and performing a thorough examination of the ocular anatomy. The correct answer is related to the principle of preventing angle closure in the fellow eye by identifying and addressing any risk factors.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not address the underlying risk factors for angle closure in the fellow eye.
**Option B:** This option is incorrect because it does not provide a clear mechanism for preventing angle closure in the fellow eye.
**Option C:** This option is incorrect because it does not address the specific risk factors associated with angle closure in the fellow eye.

**Clinical Pearl / High-Yield Fact**
In patients with a history of acute congestive glaucoma, the fellow eye is at increased risk of developing angle closure, and prophylactic laser peripheral iridotomy can significantly reduce this risk.

**Correct Answer:** D. Prophylactic laser peripheral iridotomy.