Acute orbital compartment syndrome is defined as an acute elevation of intraorbital pressure with resultant rapid ocular dysfunction. Patients typically present with ocular pain, proptosis, and blurry vision (Figure 194-1). Clinical signs of an acute orbital compartment syndrome include afferent pupillary defects, chemosis, decreased visual acuity, diminished retropulsion of the affected globe to direct manual pressure, elevated intraocular pressure (usually above 40 mmHg), exophthalmos or proptosis, mydriasis, ophthalmoplegia, and signs of retinal ischemia on funduscopic examinations (rare).1-40
A traumatic retrobulbar hematoma with exophthalmos of the right eye. A. Clinical photo. (Used with permission from Knoop KJ, Stack LB, Storrow AB, Thurman RJ (eds): The Atlas of Emergency Medicine, 4th ed. New York: McGraw-Hill; 2015. Photo contributor: David Effron, MD.) B. Computed tomography (CT) scan. (Used with permission from Li Y, et al: Intraorbital traumatic ophthalmic artery aneurysm: case report. Neurol India 2012; 60(6):657.)
Orbital compartment syndrome has been described in multiple clinical settings. The presentation that Emergency Physicians will most likely encounter is an acute posttraumatic retrobulbar hemorrhage leading to an orbital compartment syndrome with subsequent rapid loss of vision.1,2 Orbital compartment syndrome has been documented following burns, aggressive fluid administration, blepharoplasty, retrobulbar anesthesia, orbital and sinus surgery, orbital fractures with intraorbital emphysema, spontaneous subperiosteal hemorrhages, and spontaneous retrobulbar hemorrhages.3-9,36 Orbital compartment syndrome may also occur as the result of chronic and progressive disease processes (e.g., neoplasms, infections, inflammations).10
Acute orbital compartment syndrome demands prompt recognition because irreversible loss of vision (even permanent blindness) occurs without rapid treatment.11 Once the diagnosis of an acute orbital compartment syndrome is made, emergent surgical intervention is indicated. An immediate lateral canthotomy and cantholysis are indicated within 1 hour of injury and ocular dysfunction.32,40 Medical interventions aimed at reducing intraocular pressure (e.g., mannitol, acetazolamide, topical beta-blockers) should be considered adjunctive therapy and not a substitute for surgical intervention.
ANATOMY AND PATHOPHYSIOLOGY
The orbit is a closed space posterior to the orbital septum and contained within the bony orbit. The lateral wall of the orbit is formed by the zygomatic bone. The posterior wall is formed by the sphenoid bone. The medial wall is formed by the ethmoid bone. The roof is formed by the frontal bone. The floor is formed by the maxillary bone. The globe is enclosed in a fascial envelope within the bony orbit.
The medial and lateral canthal tendons provide structural fixation of the eyelids to the orbital rim. The lateral canthal tendon (LCT) is located posterior and inferior to the lateral canthal fold (Figure 194-2). The LCT originates from the superior and inferior lateral tarsal plates (Figure 194-2) and ...