Other signs of a blow-out fracture are air within the orbit (which has entered from the maxillary or ethmoid sinuses), an indistinct orbital floor on occipitomental views and opacification of the sinuses due to blood within them. An air-fluid level may be seen in the maxillary sinus. The fracture fragments are rarely demonstrated on plain films.
If the inferior rectus muscle or its sheath herniates through the fracture and becomes trapped, it may be compromised resulting in diplopia on looking down or straight ahead. Mild or transient diplopia can occur simply due to the periorbital oedema or haemorrhage. A CT scan is indicated if there is diplopia or restriction of eye movements, and to assess the extent of the injury. Direct coronal CT scans (with the patient prone) are best for demonstrating blow-out fractures. In the supine position, fluid and debris in the maxillary antrum can layer against the orbital floor and obscure soft tissue herniating through the fracture.For those patients in whom direct coronal scans are not possible (for example due to other injuries or if the patent is unable to co-operate), axial CT scans with coronal reconstructions are an alternative method of imaging, particularly with the use of multidetector CT .
The treatment of pure orbital blow-out fractures is often conservative but orbital floor repair may be necessary if there are complications such as inferior rectus muscle compromise. Surgery is rarely needed for medial wall fractures. Rarely fragments from an orbital floor fracture buckle up into the orbit, an injury referred to as a "blow-in" fracture.
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