Lateral Orbital Canthotomy

Orbital compartment syndrome (OCS) is caused due to rapidly increasing intra-orbital pressure and can lead to permanent blindness. OCS is a sight-threatening condition, originally described by Gordan and McRae in 1950 in a case following zygoma fracture repair. OCS is secondary to ischemia of the optic nerve and related retinal function, and a lack of perfusion can lead to irreversible loss of vision. OCS is a type of compartment syndrome, and as with other compartment syndromes, rapidly increasing intra-compartment pressures are related to significant morbidity and permanent damage. OCS occurs as a result of mass effect within the confines of the orbit; any process that can cause an increase in intraorbital pressure can lead to OCS. Intraorbital pressures can increase due to both hemorrhage and non-hemorrhagic processes, such as fluid accumulation. Non-traumatic causes of hemorrhage include iatrogenic procedures such as orbital, eyelid, and lacrimal surgeries. Orbital hemorrhage can also be caused by commonly used anesthetic procedures such as peribulbar or retrobulbar injections of localized anesthetics. Valsalva-related hemorrhage in the setting of sinonasal carcinoma, orbital-lymphatic malformation-related hemorrhages, extraocular tumors causing metastases has also been demonstrated as causes of OCS.  Non-hemorrhagic causes of OCS include processes such as prolonged prone surgery (such as spinal surgery), facial and periocular burns, and massive fluid resuscitation for severe burns, all of which can lead to third-spacing of fluid within the orbital compartment. Uncommon causes of OCS include orbital emphysema in the setting of associated paranasal sinus fractures. All emergency physicians must also be wary of orbital cellulitis, regardless of the presence of an associated abscess, as a possible cause of OCS. OCS is a serious ophthalmologic emergency, regardless of etiology, and all emergency physicians should be able to clinically diagnose this condition and have an understanding of lateral orbital canthotomy and cantholysis (LOC) procedure in order help prevent permanent vision loss. OCS can lead to proptosis of the globe, which leads to stretch tension on the optic nerve in addition to the compressive forces of the intra-compartment pressure. The goal of LOC is to free the eyelid from its lateral attachment to the bony orbit, thus releasing the pressure that has accumulated within the closed orbital compartment. While emergent ophthalmologic consultation is ideal for intervention, optic nerve ischemia due to OCS can develop very rapidly. Improved visual outcomes can be achieved if interventions such as LOC are performed promptly (ideally within 2 hours of presentation).