One snip lateral canthotomy

One Snip lateral canthotomy
Cite this article as:
Morgenstern, J. One snip lateral canthotomy, First10EM, March 13, 2023. Available at:

The lateral canthotomy is a core emergency medicine procedure. It was one of the earliest topics covered on First10EM. Early intervention improves outcomes, but despite that, ED physicians frequently delay performing the procedure until the arrival of a specialist. (Beams 2016) A “one-snip” approach has been described that, based on limited cadaveric studies, is equally effective at relieving intraocular pressure while simplifying the procedure. (Blandford 2018; Yarter 2023) (A related procedure, called the ‘vertical split’ adds a second cut through the upper eyelid, and is widely used for elective surgeries, as well as having cadaveric evidence of efficacy.) (Elpers 2020) Although the evidence is limited, the anatomic effect is identical, and failure is immediately identifiable (no decrease in intraocular pressure), allowing one to proceed with a more traditional surgical approach. Therefore, I think this is a reasonable first technique for this rare, vision threatening emergency.


A 21 year old man was minding his own business on a street corner, when out of nowhere two dudes just jumped him. His primary injury appears to be to his right eye. He is complaining of a lot of eye pain and blurred vision. On exam, you note proptosis and an afferent pupillary defect. The ophthalmologist is covering at another hospital and is at least an hour away. She asks you to proceed with a lateral canthotomy. However, as you have never performed the procedure before, the ophthalmologist describes a slightly simpler approach that only requires a single cut. 

My approach

Explain the procedure to the patient, and obtain consent if possible.

Although pain can probably be adequately controlled with local anesthetic, this is a high anxiety scenario, so as long as it isn’t going to result in a significant delay, I would offer procedural sedation.

Clean the skin with chlorhexidine.

The goal is to make a single cut, starting approximately 5 mm medial to the lateral canthal angle, extending approximately 1.5 cm in length, running perpendicular to the eyelid margin:

First, inject local anesthetic with epinephrine along the line of the planned cut. (Ignore the needle in the picture – direct the needle tip away from the globe.)

Next, place a straight mosquito hemostat along the planned incision line, and clamp for 15-60 seconds to minimize bleeding.

Finally, cut through all layers of tissue with iris or tenotomy scissors.

After performing the procedure, recheck the patient’s intraocular pressure. There should be an immediate and dramatic drop, back into the normal range.

Images from Yarter 2023:

Images from Blandford 2018:


Thanks to EMCrit for bringing this paper to my attention.

We tend to think about this procedure in the context of trauma, but remember that orbital compartment syndrome can also occur from medical etiologies such as infections, cancer, and spontaneous retrobulbar hemorrhage.

Other FOAMed Resources

Lateral Canthotomy – procedure guide



Beams O, Levine B, Passarello B, Papas M. 380 Lateral Canthotomy by Emergency Physicians Significantly Decreases the Risk of Vision Loss in Patients With Traumatic-Associated Elevated Intraocular Pressure Annals of Emergency Medicine. 2016; 68(4):S145-.

Blandford AD, Young JM, Arepalli S, Li A, Hwang CJ, Perry JD. Paracanthal “One-Snip” Decompression in a Cadaver Model of Retrobulbar Hemorrhage. Ophthalmic Plast Reconstr Surg. 2018 Sep/Oct;34(5):428-431. doi: 10.1097/IOP.0000000000001032. PMID: 29369152

Elpers J, Areephanthu C, Timoney PJ, Nunery WR, Lee HBH, Fu R. Efficacy of vertical lid split versus lateral canthotomy and cantholysis in the management of orbital compartment syndrome. Orbit. 2021 Jun;40(3):222-227. doi: 10.1080/01676830.2020.1767154. Epub 2020 May 27. PMID: 32460574

Yarter JT, Racht J, Michels KS. Retrobulbar hemorrhage decompression with paracanthal “one-snip” method: Time to retire lateral canthotomy? Am J Emerg Med. 2023 Feb;64:206.e1-206.e3. doi: 10.1016/j.ajem.2022.11.027. Epub 2022 Nov 21. PMID: 36564334

Photo by Glen Carrie on Unsplash

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