**Question:** Prophylactic management of the other eye in case of acute primary angle closure glaucoma/PACG (March 2013).

**Core Concept:** Acute primary angle closure glaucoma (PACG) is a life-threatening emergency that occurs when the anterior chamber angle becomes blocked, leading to a sudden rise in intraocular pressure (IOP), which can cause damage to the optic nerve and vision loss. Prophylactic management aims to prevent the development of PACG in the fellow eye by reducing IOP.

**Why the Correct Answer is Right:** The correct answer is C, which recommends close monitoring and early intervention if necessary. This is because, in the event of acute primary angle closure in one eye, the other eye is at a high risk of developing PACG due to the shared anatomical structures and the risk of miosis (constriction of the pupil) from the painful eye, which may further compromise the drainage angle.

**Why Each Wrong Option is Incorrect:**

A. Injecting medications: This option is incorrect because it does not address the high-risk status of the fellow eye and may not be effective in preventing PACG development.
B. Surgery: Surgery is not the primary prophylactic measure for the fellow eye, as close monitoring and early intervention are more appropriate and less invasive.
G. Laser peripheral iridotomy (LPI): LPI is a treatment for acute primary angle closure, not prophylactic management for the fellow eye.

**Why Close Monitoring is Needed:**

Prophylactic management of the other eye in case of acute primary angle closure involves close monitoring because:

1. Early identification of PACG risk factors: Close observation allows for early detection of risk factors such as miosis (constricted pupil) and increased IOP. Detecting these factors promptly is crucial to initiate appropriate treatment before significant damage occurs.
2. Prompt intervention: Early intervention, such as laser peripheral iridotomy (LPI) or IOP-lowering medications, can prevent the development of PACG in the fellow eye. Close monitoring ensures that the necessary treatment is administered promptly when required.
3. Reducing the risk of blindness: Close monitoring reduces the risk of blindness due to delayed diagnosis and treatment in the fellow eye.

**Clinical Pearl:**

Prophylactic management of the other eye in case of acute primary angle closure involves close monitoring and early intervention to prevent the development of acute primary angle closure glaucoma (PACG) and preserve visual function. This concept is also applicable in cases of bilateral angle closure glaucoma (BACG) and bilateral angle closure-related ocular hypertension (BACOH).