Orbital floor fractures are produced by two distinct mechanisms. The 1st is a true “blowout” fracture where all the energy is transmitted from a blunt object to the globe, causing increased orbital pressure blowing out either the orbital floor (most frequently) or medial wall. Fists and balls are the most common causative agents. This mechanism of injury is more likely to cause entrapment and globe injury. The 2nd mechanism of injury occurs when the energy from the blow is transmitted to the infraorbital rim, causing a buckling of the orbital floor. Patients with blowout fractures have periorbital ecchymosis and lid edema but may also sustain globe injuries, including chemosis, subconjunctival hemorrhage, or infraorbital numbness from injury to the infraorbital nerve. Other globe injuries seen with orbital wall fractures include corneal abrasion, hyphema, enophthalmos, proptosis, iridoplegia, dislocated lens, retinal tear, retinal detachment, and ruptured globe. Diplopia with upward gaze suggests entrapment of the inferior rectus or its supporting structures. Diplopia with lateral gaze suggests entrapment of the medical rectus muscle. Periorbital subcutaneous emphysema is frequently seen with orbital wall fractures because of the proximity to the sinuses.
Management and Disposition
Maxillofacial CT best identifies orbital wall fractures. Treat patients without eye injury or entrapment conservatively with ice and analgesics, and refer for follow-up in 2 to 3 days. Treat patients with blood in the maxillary sinus with antibiotics. Consult ophthalmology in patients with a true blowout fracture, as 30% of these patients sustain a significant globe injury. Immediately consult a facial trauma surgeon for patients with entrapment, as muscle necrosis may occur if muscle blood supply is compromised by the entrapment.
Enophthalmos, limited upward gaze, diplopia with upward gaze, or infraorbital anesthesia from entrapment or injury to the infraorbital nerve should heighten suspicion of an orbital floor fracture.
Compare the pupillary level on the affected side with the unaffected side, since it may be lower from prolapse of the orbital contents into the maxillary sinus. Subtle abnormalities may be appreciated as an asymmetric corneal light reflex (Hirschberg reflex).
Subcutaneous emphysema, a soft-tissue teardrop along the roof of the maxillary sinus on plain film, or an air-fluid level in the maxillary sinus on plain film should also be interpreted as evidence of an orbital floor fracture.
Patients with orbital wall fracture may present with subcutaneous emphysema after blowing their nose or air bubbles emanating from the tear duct.
Carefully examine the eye for visual acuity, hyphema, or retinal detachment, and the nose for septal hematoma.
Orbital Floor Fracture. Sustained from blunt trauma to infraorbital rim causing buckling of the orbital floor. Maxillofacial CT is similar to that in Fig. 1.43. Infraorbital hypesthesias and lack of entrapment suggest the buckling mechanism of injury. (Photo contributor: Lawrence B. Stack, MD.)