A blow-out fracture is a fracture of one of the walls or floor of orbit with an intact orbital rim. It is the commonest orbital fracture, with orbital floor fractures more common than medial wall fractures. It is produced by a blow to the orbit which suddenly increases the intraorbital pressure, fracturing a portion of the orbital bony lining.

Complications of blowout fracture include enophthalmos due to increased globe volume, diplopia on vertical gaze due to tissue entrapment, and globe injury. Orbital emphysema or hemorrhage may occur. Injury to the inferior orbital nerve may cause facial numbness.

Indications for surgical repair include significant enophthalmos, significant diplopia, muscle entrapment, and large area fractures. Repair should be prompt to avoid longstanding complications. 

Case credit: Bernard Ng and Dr Laughlin Dawes