**Question:** A young adult presents with proptosis and pain in eye after 4 days of trauma to eye. Chemosis, conjunctival congestion and extraocular muscle palsy with inability to move eye are seen. Investigation of choice:

A. Computerized Tomography (CT) scan
B. Fundoscopy
C. Magnetic Resonance Imaging (MRI)
D. Ultrasound B-mode

**Correct Answer:** .

**Core Concept:** Traumatic orbital injury is a condition caused by external force to the orbit that can lead to damage to the eye and surrounding structures.

**Why the Correct Answer is Right:**

Proptosis, conjunctival congestion, and extraocular muscle palsy are all indicative of orbital trauma and are the main reasons for choosing MRI as the investigation of choice. MRI provides high-resolution images of the orbital contents, including the eye, optic nerve, and intraorbital structures. It can detect soft tissue edema, hemorrhage, and fractures that may not be apparent on CT scans. In addition, MRI is less affected by superimposition of bone structures, making it more sensitive in detecting orbital injuries.

**Why Each Wrong Option is Incorrect:**

A) Computerized Tomography (CT) scan: While CT scans are useful for detecting bone fractures and orbital hemorrhage, they are less sensitive in detecting soft tissue injuries and edema. These injuries are crucial in understanding the extent of the orbital trauma.

B) Fundoscopy: Fundoscopy is an examination of the fundus or back of the eye. It is not a suitable investigation for orbital trauma as it focuses on the retina and optic nerve rather than the orbital contents.

C) Magnetic Resonance Imaging (MRI): Although MRI is essential in assessing orbital trauma, it is not the only option. MRI can be expensive and may not be readily available in some settings. In such cases, CT scan may be used as a second-line investigation.

D) Ultrasound B-mode: Ultrasound is not recommended for evaluating orbital trauma as it is less sensitive in detecting soft tissue injuries, hemorrhage, and fractures. MRI is generally preferred for assessing orbital injuries due to its superior soft tissue resolution and ability to identify orbital hemorrhage and fractures.

**Clinical Pearl:** In cases where MRI is not accessible, a combination of clinical examination, CT scan, and orbital ultrasound can be used to assess orbital trauma. However, MRI remains the gold standard due to its superiority in detecting soft tissue injuries, hemorrhage, and fractures.

**Explanation of the Core Concept and Why Each Wrong Option is Incorrect:**

MRI is the gold standard for assessing orbital trauma as it provides high-quality images of the orbital contents, including the eye, optic nerve, and soft tissues. It can detect hemorrhage, fractures, and soft tissue injuries, which are crucial in determining the extent of the injury.

**Core Concept Explanation:**

Orbital trauma can lead to various complications, including optic nerve damage, intraocular hemorrhage, and orbital hemorrhage. MRI is essential in detecting these complications accurately, as it provides high-resolution images of the orbital contents