**Question:** A child with a unilateral white reflex raised IOP. The required investigations are:

A. Fundus examination
B. Pupillary examination
C. Visual field testing
D. Slit lamp examination

**Core Concept:** The white reflex is a bright, white, and dazzling reflex seen in the pupil due to the reflection of light off the crystalline lens or the pupillary sphincter. A raised intraocular pressure (IOP) can cause a white reflex to be unilateral, indicating potential glaucoma.

**Why the Correct Answer is Right:**

1. **A. Fundus examination:** This test is essential as it allows us to visualize the optic disc, retina, and other intraocular structures. Raised IOP can lead to optic nerve damage, and thus, evaluating the optic disc is crucial in detecting glaucoma.
2. **B. Pupillary examination:** Assessing pupillary size, shape and the position of the pupil helps in differentiating between various types of glaucoma.
3. **C. Visual field testing:** This helps to evaluate the central visual field and detect peripheral visual field defects, which are common in glaucoma.
4. **D. Slit lamp examination:** Evaluating the anterior segment can reveal other ocular conditions and medications that can affect intraocular pressure.

**Why Each Wrong Option is Incorrect:**

1. **Option A (Fundus examination):** Although important, fundus examination alone may not suffice to diagnose glaucoma, as it does not directly measure IOP.
2. **Option B (Pupillary examination):** Measuring pupillary diameter or shape isn't sufficient to diagnose glaucoma as it doesn't provide information about IOP.
3. **Option D (Slit lamp examination):** While evaluating the anterior segment can reveal other ocular conditions or medications affecting IOP, it is not the primary test to diagnose raised IOP.

**Clinical Pearl:** A white reflex in a child should prompt a thorough ophthalmological evaluation. The combination of fundoscopy, pupillary examination, visual field testing, and slit lamp examination is crucial for diagnosing raised intraocular pressure and ruling out other ocular conditions causing a white reflex.

**Core Concept:** Early diagnosis and intervention for raised IOP in children can prevent visual impairment and blindness.