Orbital Compartment Syndrome
Orbital compartment syndrome (OCS) occurs as a result of an acute rise in orbital pressure from hemorrhage (Fig 6-7) or introduction of air into the orbit. It most commonly occurs in association with trauma, surgery, retrobulbar or peribulbar injections, or preexisting orbital disease.
Figure 6-7 Orbital compartment syndrome (OCS). Axial CT image shows OCS on the right side secondary to a retrobulbar hemorrhage in a teenaged patient struck by a softball. Image demonstrates proptosis and the presence of intraconal blood.
(Courtesy of M. Reza Vagefi, MD.)
Because the orbit has a fixed volume, there is limited room to accommodate any expansion of its contents. As orbital pressure increases, associated vision loss can be attributed to 1 of the 4 following mechanisms:
central retinal artery occlusion
direct compressive optic neuropathy
compression of optic nerve vasculature
ischemic optic neuropathy that results from stretching of nutrient vessels
Examination of a patient with OCS reveals decreased vision, afferent pupillary defect, and increased IOP. Elevated IOP in cases of OCS reflects the increased orbital pressure and is not indicative of glaucoma. In addition, a tight orbit with decreased extraocular movements and proptosis is often observed. Patients should undergo emergent decompression of the orbit, as described in Figure 6-8. Because vision loss can progress rapidly, this procedure should not be delayed for orbital imaging. If OCS is present in a patient with antecedent eyelid or orbital surgery, the wound should be opened and the hematoma evacuated, followed by exploration and cautery of active bleeding. Otherwise, decompression is most easily achieved by lateral canthotomy and cantholysis, in which the eyelids are disinserted from the lateral orbital rim, allowing the orbital volume to expand anteriorly. Lateral canthotomy alone does not sufficiently decrease orbital pressure; inferior cantholysis and sometimes superior cantholysis are also required. Careful monitoring and reassessment of the ophthalmic examination are necessary to determine whether further surgical intervention is needed.
Lima V, Burt B, Leibovitch I, Prabhakaran V, Goldberg RA, Selva D. Orbital compartment syndrome: the ophthalmic surgical emergency. Surv Ophthalmol. 2009;54(4):441–449.
Excerpted from BCSC 2020-2021 series: Section 10 - Glaucoma. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.