Orbital emphysema is an uncommon condition, which is defined as the presence of air within the fascial layers of the orbit [1]. It occurs most commonly after orbital/facial trauma or surgery, e.g. dacryocystorhinostomy, orbital decompression and functional endoscopic sinus surgery. Rarely, it can occur with sinusitis (especially with gas-forming microorganisms), nose blowing, sneezing, during air travel with pressure changes or Valsalva manoeuvre [1–7].

Orbital emphysema occurs mostly from defects in the orbital walls, especially the medial lamina papyracea and orbital floor (Fig. 20.1). Air migrates from the ethmoid, the maxilla and, less commonly, the frontal sinus through the defect into the orbit. Air enters the orbit intermittently during episodes of acute rise in pressure in the respiratory passage, which can happen after nose blowing, coughing or sneezing [3]. Serious orbital emphysema may result from a small fracture site or when orbital tissues fall back to the defect acting as a one-way valve [3]. Subsequent pressure rise may build up within the orbit resulting in an orbital compartment syndrome (please see previous chapter). If not promptly identified and treated, it can result in severe and permanent visual loss. Fortunately, most cases of orbital emphysema are benign and self-limiting requiring only close monitoring and advice against nose blowing or deliberate Valsalva action [3].