**Question:** Earliest sign of Acute Anterior Uveitis is

A. Conjunctival injection
B. Anterior segment pain
C. Iris edema
D. Vitreous opacity

**Core Concept:**
Acute Anterior Uveitis, also known as iridocyclitis or iritis, is an inflammation of the anterior uvea, which is the middle layer of the eye composed of the iris, ciliary body, and choroid. It is a manifestation of an underlying systemic or ocular inflammation.

**Why the Correct Answer is Right:**
The correct answer, **B. Anterior segment pain**, is the earliest sign of Acute Anterior Uveitis. This sign arises due to the inflammation affecting the iris and ciliary body, which contain pain receptors. As the inflammation progresses, additional signs like conjunctival injection (A), iris edema (C), and vitreous opacity (D) may develop.

**Why Each Wrong Option is Incorrect:**
Option A (Conjunctival injection) occurs later in the disease process as the inflammation affects the conjunctiva. Option C (Iris edema) is also a later sign, as edema involves the entire iris and can be confused with a pupillary defect. Option D (Vitreous opacity) is a late sign, as the inflammation affects the posterior segment of the eye and can cause vitreous opacity.

**Clinical Pearl:**
The early recognition of anterior uveitis symptoms, particularly pain, is crucial for timely diagnosis and treatment, which helps prevent complications such as cataract formation, glaucoma, and vision loss.

**Correct Answer:** B. Anterior segment pain