Orbital Compartment Syndrome: When to Perform Lateral Canthotomy 

Authors: Joseph McEachon, DO, Blake Briggs, MD

Introduction

Orbital compartment syndrome (OCS) is a vision-threatening emergency. It’s characterized by rapid elevation of intraorbital pressure leading to decreased perfusion of the optic nerve and retina. If untreated, ischemia of the optic nerve and retina can occur within a short time frame (60-100 minutes), resulting in permanent visual loss [1]. Because the orbit is a rigid compartment formed by bony walls and constrained anteriorly by the eyelids and orbital septum, even small increases in orbital volume can produce dramatic increases in intraocular pressure (IOP) (recall normal IOP <20 mmHg). EM physicians must rapidly recognize OCS and perform emergent decompression when indicated (lateral canthotomy and cantholysis).  Let’s review when to do this and how.

Pathophysiology

Blunt trauma is the most common injury to the orbit that can cause an orbital hemorrhage. When this occurs in a location behind the orbital septum (post septal / retrobulbar space) this can become vision threatening. A retrobulbar hemorrhage can cause a rapid increase in intraorbital pressure, behaving as a closed compartment. [2]. Other, less common causes include: fulminant orbital cellulitis, severe burns, and orbital emphysema [3].  

Clinical Signs

The most common clinical findings that can be suggestive of OCS are proptosis, decreased visual acuity, afferent pupillary defect, elevated IOP [1, 2]. Additional signs can include: increased firmness of the eye, chemosis, subconjunctival hemorrhage, taut eyelids. An IOP >30 mmHg in the setting of visual disturbances should raise consideration for emergency lateral canthotomy. It should be noted that some sources say >40 mmHg. We prefer the more sensitive value, and it should be noted there is no absolute threshold that is agreed upon [4, 5, 6, 7].  

Diagnosis

OCS is a clinical diagnosis meaning there is no need to wait for imaging to confirm prior to treatment [1].Indications to perform a lateral canthotomy and cantholysis generally is when retrobulbar hemorrhage is suspected (blunt trauma), AND one of the following: 

• -elevated IOP >30 mmHg
• -vision loss
• -relative afferent pupillary defect (RAPD)
• -proptosis

Not all the clinical signs may be present, but in the right clinical context (blunt trauma to the orbit) displaying even one clinical sign should prompt consideration. Another indication to perform the procedure can be findings suggestive of OCS on computer tomography (CT) imaging: stretching of the optic nerve, retrobulbar hemorrhage with proptosis, or posterior globe tenting [4].  If this is found on CT, an attempt at obtaining IOP and preparing for lateral canthotomy should ensue. Again, imaging is not required and should not delay treatment. If clinical concern is low, or exam is limited by eyelid swelling or decreased level of consciousness, a rapid CT can be considered. Different techniques have been described for improving visualization of the orbit in the setting of severe swelling, namely twirling a q-tip on the upper eyelid or using paperclips on the upper and lower lids. [7, 8] CT of the orbit is the preferred imaging modality, but often in facial trauma CT Maxillofacial will be obtained to evaluate for other facial fractures.

Treatment

Treatment of OCS is emergency bedside lateral canthotomy and cantholysis. Emergent ophthalmology consultation is warranted, though this should not delay the procedure especially in facilities without in house ophthalmology. The only absolute contraindication to this procedure is a suspected globe rupture (suggested by: laceration to the globe, irregular pupil, hyphema, or abnormally low IOP <5 mmHg, positive seidel sign if fluorescein stain of the eye performed) [4].Complications from a lateral canthotomy can include failed procedure, infection, bleeding, mechanical injury, and scarring. These complications have better outcomes than vision loss [2]. 

Procedure Specifics

1). Anesthetize the lateral canthus area with lidocaine with epinephrine to decrease pain and bleeding. Some patients may require procedural sedation. 2). Place a set of hemostats horizontally across the lateral canthus to the lateral orbital rim for ~30-60 seconds– this will devitalize tissue and decrease bleeding [4].  3). Use small sterile scissors to make a 2 cm incision over the tissue overlying the clamp site, extending from the lateral canthus to the lateral orbital rim. 4). Retract the lower lid to reveal the inferior crus of the lateral canthus tendon. 5). Cut the inferior lateral canthal tendon (cantholysis). Your scissors should be pointed down and away from the orbit (not as pictured below).  6). Repeat IOP measurement – if successful IOP should substantially improve, if unsuccessful the superior lateral canthal tendon may need to be cut as well [2].

Post-Procedure Care

Emergent ophthalmology consultation, if not done so already. Transfer to a facility with ophthalmology is warranted. The incisions made during this procedure heal on their own without further intervention [4]. If needed, ophthalmology can make repairs at a later time.  

References:

1.     Kloss BT, Patel R. Orbital compartment syndrome from retrobulbar hemorrhage. Int J Emerg Med. 2010;3(4):521-522. doi:10.1007/s12245-010-0245-1

2.     Shah KH, Blanchard DG. Eye emergencies. In: Tintinalli JE, Ma OJ, Yealy DM, et al., eds. Tintinalli’s Emergency Medicine: A Comprehensive Study Guide. 9th ed. McGraw Hill; 2020:241.

3.     Voss JO, Bickelmann C, Hummitzsch L, et al. Success rates of lateral canthotomy and cantholysis for treatment of orbital compartment syndrome. Am J Emerg Med. 2023;66:145-150. doi:10.1016/j.ajem.2023.01.036.

4.     Ostrowski K, Miers J. Lateral canthotomy. Life in the Fast Lane (LITFL). Published September 18, 2025. Accessed March 12, 2026

5. Rowh AD, Ufberg JW, Chan TC, Vilke GM, Harrigan RA. Lateral canthotomy and cantholysis: emergency management of orbital compartment syndrome. J Emerg Med. 2009;37(4):443-449. doi:10.1016/j.jemermed.2007.10.021.

6. Vo V. Lateral Canthotomy. In: Swadron S, Nordt S, and Mattu A, eds. CorePendium. 6th ed. Burbank, CA: CorePendium, LLC. https://www.emrap.org/corependium/chapter/recVOp8GoTweO76o2/Lateral-Canthotomy#h.x2s5c5y73qlb. Updated April 15, 2026. Accessed April 19, 2026.

7. McGovern T, McNamee J, Patel N. Tips for relieving increased intraocular pressure. ACEP Now. Published March 16, 2015. Accessed April 19, 2026. Tips for relieving increased intraocular pressure

8. Alvarez A. Trick of the trade: retracting swollen eyelids. Academic Life in Emergency Medicine (ALiEM). Published June 10, 2020. Accessed April 19, 2026. Trick of the trade: retracting swollen eyelids