Contributor: Taylor Lynch, MD

Educational Pearls:

What is orbital compartment syndrome, and how is it assessed in the emergency room?

Orbital compartment syndrome (OCS) is an emergent ophthalmic condition in which intraorbital pressure in the orbital compartment rises dramatically, compromising perfusion of the optic nerve and retina, leading to risk of irreversible vision loss.
OCS occurs in the context of traumatic lesions with retrobulbar hemorrhage.
Intraocular pressures (IOP) are measured via tonometry as a surrogate for intraorbital pressures, with emergent pathology being present when IOP exceeds 30-40 mmHg (normal being around 20 mmHg).

What might be some physical exam findings beyond increased IOP for orbital compartment syndrome?

Proptosis (physical outward protrusion of eye) with resistance to being pushed posterior.
Afferent pupillary defect (when the non-impacted eye has light shown into it, the impacted eye will have pupillary constriction, and when light is removed it will begin to dilate, but when light is shown into the impacted eye, it will not constrict and continue to dilate).
Generalized complaints of vision loss or an inability to move the eye.

What is the treatment for orbital compartment syndrome?

Lateral canthotomy must be performed immediately upon clinical suspicion as permanent vision loss can occur within minutes to hours.
Lateral canthotomy Step-by Step:
- Ideally have the patient sedated or highly cooperative.
- Numb and vasoconstrict the surrounding eye/orbital skin tissue with lidocaine and epinephrine.
- Take hemostats and clamp the interior and exterior eyelid at the lateral canthus at a 90º angle towards the orbital rim for 30-60 seconds to further devascularize the region.
- Take iris scissors and cut laterally to the orbital bone/rim to reveal the lateral lanthal tendon.
- Cut the inferior crus of the lateral lanthal tendon as this will provide the most significant reduction in IOP.
- Reassess IOP during each step of the procedure to measure procedure efficacy. If no pressure reduction is noted with inferior cantholysis, cutting the superior crus of the lateral canthal tendon may be required to further allow the eye to bulge out and reduce intraorbital pressure.

Big takeaways?

Ocular compartment syndrome is a rare but emergent vision threatening condition that requires immediate lateral canthotomy to reduce intraocular and intraorbital pressures.
Lateral canthotomy done within 30-60 minutes of symptom development can save the patient from permanent vision loss.

References:

Mohammadi F, Rashan A, Psaltis A, et al. Intraocular Pressure Changes in Emergent Surgical Decompression of Orbital Compartment Syndrome. JAMA Otolaryngol Head Neck Surg. 2015;141(6):562-565. doi:10.1001/jamaoto.2015.0524
Haubner F, Jägle H, Nunes DP, et al. Orbital compartment: effects of emergent canthotomy and cantholysis. Eur Arch Otorhinolaryngol. 2015;272(2):479-483. doi:10.1007/s00405-014-3238-5
Bailey LA, van Brummen AJ, Ghergherehchi LM, Chuang AZ, Richani K, Phillips ME. Visual Outcomes of Patients With Retrobulbar Hemorrhage Undergoing Lateral Canthotomy and Cantholysis. Ophthalmic Plast Reconstr Surg. 2019;35(6):586-589. doi:10.1097/IOP.0000000000001401

Summarized by Dan Orbidan, OMS2 | Edited by Dan Orbidan and Jorge Chalit, OMS4

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Episode 986: Lateral Canthotomy in Emergency Settings

Emergency Medical Minute