Ocular trauma is a common problem in the emergency department, accounting for at least 20 % of eye-related admissions. It's mostly the result of polytraumatic accidents such as vehicle, sports and industrial accidents or physical assault. There can also be a solely orbital pathology such as a foreign body accident.

Urgent assessment means fast care and thus prevention of permanent or partial visual loss and sequela of any kind such as movement impairment. Prompt radiological recognition of orbital pathology is a morbidity reducing part of emergency radiology.

CT is the first diagnostic tool of preference since it is fast, available and can also visualize the intracranial structures. Orbital noncontrast CT images are acquired from the frontal to the maxillary sinuses with 0.5-1.5 mm thickness and then reformatted in three planes in soft tissue and bone windows.

The orbital anatomy can be divided into three parts; bone, globe and soft tissue.

1. Bony Anatomy

Orbital bones form a conical structure that points posterolaterally.

Medial wall: Maxillary bone, lamina papricea of the ethmoid bone and the sphenoid bone from anterior to posterior.  Laminae papricea is very thin, hence the weakest part of the bony orbit is the medial wall.
Floor: Orbital plate of the maxilla, the orbital process of the palatine bone and the orbital surface of the zygomatic bone. Inferior blow out fracture commonly occurs at the orbital plate of maxilla since it’s the thinnest part of the inferior wall.
Superior wall: Frontal bone.
Lateral wall: Zygomatic bone

2. Globe and soft tissue anatomy

The surface of the globe: Retina, vascular layer and sclera.

The cavities: Anterior chamber, posterior chamber and vitreous cavity.

The anterior chamber lies between the cornea and the iris, and the posterior chamber is between the iris and the lens. The vitreous cavity (or the posterior segment) is the space behind the lens.

The soft tissue components: Muscles and nerves.

The space posterior to the globe is divided into two parts by the muscle cone. The muscle cone is formed by six muscles, inside this structure is the intraconal space. The intraconal space is filled with the orbital fat, optic nerve, ophthalmic artery, superior ophthalmic vein, lymphatics, and smaller vessels. The optic nerve can either be straight or curved. The extraconal space is the area between the intraconal space and the bony orbit.

A proposed reading may start with the bones and working the way inward; the extraconal space, intraconal space and lastly the globe.