Lateral Canthotomy 1

History

Orbital compartment syndrome (OCS) leading to blindness was first published on in Plastics and Reconstructive Surgery in 1950.^[1] From here, lateral canthotomy was established as an operative procedure, with early accounts of drains being placed to help aid in decompression. For many subsequent years, the procedure was reserved for the operative suite and not considered within the Emergency Medicine provider’s scope of practice.^[2] Through advancing medical technologies and concurrent modification and simplification of the procedure, lateral canthotomy has come into the Emergency Medicine physician’s scope of practice. In 1981, the first ED-based lateral canthotomy was documented.^[3]

Anatomy

The orbital compartment is a complex and compact area of anatomy, containing many nerves (most notably the optic nerve), muscle bellies and their associated tendons, and blood vessels. The eye is held in the socket in part by the inferior and superior orbital septa and their associated attachment points including the medial and lateral canthi. When blood accumulates in the orbital compartment (i.e. from a retrobulbar hematoma), it rapidly increases the pressure on structures contained within. Other causes of OCS include intraocular hematoma, sub-periosteal hematoma, and sinus fractures with orbital emphysema. Outside of trauma, the most common causes of OCS are facial surgery and orbital cellulitis.^[5][6] When the optic nerve is compressed, injury can occur quickly, and current literature notes improved visual outcomes when intervention is completed within two hours.^[7]

To release the pressure, the lateral canthus with its component inferior and superior crus are cut, allowing for anterior protrusion of the eye and other orbital compartment content.

Indications

Lateral canthotomy is reserved for acute OCS. Causes of acute OCS are discussed above in the Anatomy section. With acute OCS, patients will note pain, limited eye movement, and visual impairment varying from decreased or blurry vision to full vision loss. In the setting of pathologic anatomical changes causing a potential for acute OCS (ex: retrobulbar hematoma), orbital compartment syndrome is diagnosed clinically. Signs of acute OCS include proptosis, decreased visual acuity in the affected eye, limited extraocular movement, afferent pupillary defect, and increased intraocular pressure.^[8]

If there is diagnostic uncertainty or additional data points are desired, intraocular pressure measurement with a soft cut point of 40 mmHg is often used to further support the need for lateral canthotomy in addition to clinical features.

Contraindications

The only absolute contraindication to lateral canthotomy is globe rupture. This can be diagnosed clinically or by imaging (CT).

Equipment

Betadine or other antiseptic, lidocaine with epinephrine and injection materials, forceps or lid retractors, straight hemostat, Iris or Stevens scissors.

Technique

The surgical technique for lateral canthotomy is outlined in detail in the procedure page.

Complications

As with any procedure in which tissue is violated, infection and bleeding can occur but are rare, especially with proper technique.

Injury to the corneal in the form of corneal abrasions can occur, especially given the pyroptotic eye. Globe rupture can also occur. Careful lid retraction and instrument handling can help prevent this.

Incomplete or complete loss of normal lid suspension can occur, leading to improper lid positioning, which is a largely cosmetic sequela.^[8]