Procedure: Lateral Canthotomy

The Procedure

Hello again from the Emergency Procedures team, with an ophthalmological procedure

Lateral canthotomy and cantholysis

Today we cover lateral canthotomy and cantholysis, with a guide made in partnership with a recent publication in Australasian Emergency Care. Thanks to Kevin Ostrowski for a for your expert input into this article and our video.

Peisah RI, Ostrowski K. Emergency management of orbital compartment syndrome: Lateral canthotomy and cantholysis case series. Australas Emerg Care. 2024 Sep 27:S2588-994X(24)00055-1.

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So, without further ado…here is the video

The rationale…

What is orbital compartment syndrome and how is it treated?

Orbital compartment syndrome is a sight-threatening emergency usually caused by intra-orbital haemorrhage post trauma. Bleeding into the fixed orbital space increases pressure resulting in ischaemia of the optic nerve and retina with potentially irreversible visual loss. It is treated by lateral canthotomy and cantholysis.

When should I perform lateral canthotomy and cantholysis?

• Blunt eye trauma – (suspected retrobulbar haematoma)

PLUS, any of the following

• Decreased visual acuity
• Raised intraocular pressure (>40 mmHg)
• Relative afferent pupillary defect
• Proptosis

OR

• CT scan findings of orbital compartment syndrome, which are:
• Stretching of the optic nerve
• Tenting of the globe
• Retrobulbar haemorrhage with proptosis

This is a sight saving procedure with low risk of significant complications. The procedure should be performed as soon as possible once the diagnosis is made due to its time critical nature and to reduce the risk of permanent visual loss.

Should I get a CT to confirm suspected orbital compartment syndrome before the procedure?

Not usually.

Orbital decompression is a low morbidity procedure, with simple incisions that will often heal without intervention or are easily repaired, if you suspect orbital compartment syndrome you should perform the procedure without CT imaging, as diagnostic delay worsens outcomes.

Where clinical assessment is impaired by reduced LOC, or a closed swollen eye and orbital compartment syndrome is considered possible by unlikely, a rapid CT can be considered.

CT scan findings suggestive of orbital compartment syndrome include retrobulbar haemorrhage with proptosis, stretching of the optic nerve and tenting of the globe.

Are there any contraindications?

Suspected globe rupture is a relative contraindication which is suggested by globe laceration, irregular pupil, hyphaema, or intraocular pressure < 5 mmHg.

There is some overlap between the signs of globe rupture and orbital compartment syndrome in the trauma patient (diffuse chemosis, ophthalmoplegia). If in doubt lateral canthotomy should be performed while avoiding pressure on the eye.

Is there any strong evidence for the pressure cut off or 40 mmHg?

Normal intraocular pressure is 10 – 21 mmHg.

Multiple papers cite a pressure ≥40 mmHg as an indication for lateral canthotomy, evidence supporting this strict cutoff is limited. We suggest if the eye can see no better than hand motion or light perception with a pressure > 30 mmHg the procedure should be performed.

What are the potential complications of the procedure?

The most likely complication of this procedure is failure (incomplete cantholysis). If there is no improvement after incision of the inferior crus and cantholysis is confirmed then proceed to divide the superior crus of the lateral canthal tendon.

Other complications include globe injury, bleeding, infection and injury to the lacrimal ducts, although these are quite rare.

Overall, it is a low morbidity procedure with simple incisions that often heal without intervention.

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