**Question:** A patient is presented with a foreign body in the eye. Which investigation should not be done?

**Core Concept:** Foreign bodies in the eye can cause various ocular complications, and their management depends on the type of foreign body and the extent of ocular injury.

**Why the Correct Answer is Right:** In this scenario, we need to consider the type of foreign body and its potential to cause ocular damage. A foreign body in the cornea can lead to corneal ulceration, infection, and vision loss if left untreated. However, performing a detailed ocular examination, including slit-lamp biomicroscopy, fundoscopy, and presenting visual acuity, is essential to assess the extent of injury and guide appropriate management.

**Why Each Wrong Option is Incorrect:**

A. **Option A (Ophthalmoscopy):** Ophthalmoscopy is the examination of the fundus (the back part of the eye) to look for retinal hemorrhages, detachment, or other ocular injuries. In this scenario, it would not be the right investigation to perform because the patient has a foreign body in the cornea, not the fundus.

B. **Option B (Slit-lamp examination):** Slit-lamp examination is essential in evaluating the ocular surface, anterior chamber, and cornea in cases of foreign body injury. In this scenario, it would not be the right investigation to perform because the patient has a foreign body in the cornea, not the posterior segment.

C. **Option C (Ocular ultrasound):** Ocular ultrasound is used when there is suspicion of a foreign body in the vitreous cavity or retina. In this scenario, it would not be the right investigation to perform because the patient has a foreign body in the cornea, not in the vitreous cavity or retina.

D. **Option D (Fundoscopy):** Fundoscopy is performed to evaluate the fundus and retina. In this scenario, it would not be the right investigation to perform because the patient has a foreign body in the cornea, not in the fundus.

**Core Concept:** Foreign bodies in the eye can lead to various complications, and the appropriate management depends on the type and location of the foreign body.

**Why the Correct Answer is Right:** The correct investigation to perform in this scenario is **Option B (Slit-lamp examination)**. A slit-lamp examination is essential in evaluating the ocular surface, anterior chamber, and cornea in cases of foreign body injury. This examination helps identify the type, size, and location of the foreign body, as well as assess for corneal edema, hypopyon (an inflammatory exudate in the anterior chamber), and the presence of a hyphema (intravascular hemorrhage in the anterior chamber).

**Why Each Wrong Option is Incorrect:**

A. **Option A (Ophthalmoscopy):** Ophthalmoscopy is used to assess the fundus and retina, which are not relevant to a corneal foreign body.

C. **Option C (Ocular ultrasound):** Ocular ultrasound is used to evaluate the vitreous body and retina, which are not relevant