In retrobulbar hemorrhage, an increased pressure in the orbital space can lead to optic nerve compression and vascular compromise.6 Important alternative diagnoses to consider include orbital cellulitis, orbital fracture, and globe rupture.3 Retrobulbar hemorrhage should be suspected in the clinical setting of exophthalmos, proptosis, diffuse subconjunctival hemorrhage, pain, visual loss or diplopia, periorbital edema, partial or complete ophthalmoplegia, resistance to retropulsion, increased IOP, a blanched ophthalmic artery on funduscopic examination, and an afferent pupillary defect.3,4,8,9 Less commonly, periorbital crepitus and infraorbital hypoesthesia can be appreciated.3
If a patient with a retrobulbar hemorrhage is experiencing diminished vision, an emergent lateral canthotomy should be attempted. Retrobulbar hemorrhage can be difficult to diagnose in the setting of trauma. There can be damage to the optic nerve with associated edema and vision loss that is not associated with a retrobulbar hemorrhage and does not require a lateral canthotomy.3,7 A dedicated CT scan of the orbits can aid in the diagnosis, but treatment should not be delayed.8
Patients with retrobulbar hemorrhage may initially present to the ED with intact visual acuity, but as the pressure behind the globe increases, vision will diminish.3 Although the medical literature has not established a definitive timeframe, it is believed that permanent visual compromise develops between 1 to 3 hours after ischemia develops.6 Animal studies show that visual loss due to central retinal artery ischemia may be reversible up to 100 minutes.3
Not all cases of retrobulbar hemorrhage are associated with vision loss. In patients without diminished vision, conservative treatments such as bed rest, elevation of the head of the bed, ice packs, analgesia, lowering BP, and sedatives should be attempted first.5 Acetazolamide and mannitol can also be considered in consultation with an ophthalmologist.
Pneumo-orbitum
The presence of pneumo-orbitum should alert the clinician to either a communication with a paranasal sinus, a gas-forming organism, or (rarely) Munchausen syndrome.10 Unlike most case presentations, most causes of pneumo-orbitum do not involve OCS and are self-limited.11 Traumatic pneumo-orbitum without OCS has been reported in the literature.12-15 However, traumatic tension pneumo-orbitum is rare.12-16 One case report involved an elderly man with an orbital floor fracture who developed recurrent tension pneumo-orbitum after blowing his nose while intoxicated.12 Another case involved a boy with tension pneumo-orbitum that required surgical decompression.16
In a patient who has experienced trauma, the combination of proptosis, elevated IOP, and vision loss likely represent a retrobulbar hematoma or OCS. A lateral canthotomy can help relieve IOP from either condition.17,18 Orbital compartment syndrome can be caused by edema, emphysema, and caroticocavernous fistula, leading to increased orbital pressure and decreased perfusion.17,18
In a review of 10 trauma patients with OCS, all cases were intubated due to the severity of the head trauma, and all had OCS due to edema.17 In a review of eight trauma patients with OCS, all had eye pain, reduced visual acuity, and proptosis.18 Most of the patients had periorbital edema, ophthalmoparesis, a relative afferent pupillary defect (as compared to a fixed and dilated pupil), and chemosis.18,19 All of the patients with OCS required cantholysis or a lateral canthotomy.18