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The Best in FOAM Education

  • Max MacBarb, MD

An Approach to Lateral Canthotomy

A 73 year old male with a past medical history of hypertension, hyperlipidemia, CAD status post stent, presents after an assault. He was driving his car during a snowstorm and was tailgated by another car. The patient pulled his car over to the side of the road and got out of his car where he was ultimately assaulted by the driver behind him. He was hit in the head with a closed fist and knocked to the ground. Patient denies any loss of consciousness. Patient states he's on prasugrel, an antiplatelet agent. Patient is complaining of decreased vision and pain of his right eye. Patient is able to move his eyes with normal tracking and denies pain with extraocular movements.


Visual acuity in the right eye is sensitive to light. Intraocular pressure is 30-35 mmHg. No obvious globe rupture. Mild proptosis. Grade 1 hyphema.

CT orbits:

  1. Nondisplaced fracture of the right orbital floor

  2. Comminuted nasal bone fracture

  3. Right maxillary sinus hemorrhage

  4. Hemorrhage of the supra lateral compartment of the right orbit.

  5. No proptosis. Globe intact. No retrobulbar hematoma

Take Away #1 - Indications for Lateral Canthotomy

  • Primary Indications

  • Retrobulbar hematoma

  • Increased intraocular pressures over 40

  • Proptosis

  • Secondary indications

  • Afferent pupillary defect

  • Cherry red macula

  • Nerve head pallor

  • Eye Pain

Take Away #2 - The Procedure

  1. Consider procedural sedation if applicable and time allows

  2. Anesthetize the lateral canthus with 1-2% lidocaine with epinephrine

  3. Use a hemostat to clamp the lateral canthus for 30-90 seconds

  4. Cut the lateral canthus 1-2 cm

  5. Start by cutting the inferior crus

  6. Remeasure the intraocular pressure. If still elevated cut the superior crus

  7. If pressure is still elevated take a hemostat and intentionally create an inferior blow out fracture

Take Away #3 - Calibrating the Tonopen

  1. To calibrate Reichert Tono Pen, invert device with ocular probe down

  2. Press black button twice and see “CAL”, wait for calibration to say “-UP-”, Turn ocular probe toward ceiling. Wait for screen to read “GOOD”. If “BAD” is displayed restart calibration.

Final Thoughts

  • Vision may slowly improve within 15 minutes or over 6 hours

  • EMRAP HD has card to bring to bedside if performing lateral canthotomy.

  • Resus Crisis Manual has a how to do lateral canthotomy


Max MacBarb, MD is a current second year resident at Stony Brook Emergency Medicine.


  • EMRAP Retrobulbar Hematoma Jessica Mason MD, Stuart Swadron MD, Mel Herbert MD

  • Department of Emergency Medicine, University of Maryland School of Medicine, 6th Floor, Suite 200, 110 South Paca Street, Baltimore, MD 21201, USA.

  • Resus Crisis Manual Scott Weingart MD, David Borshoff MBBS

  • Johnson D, Schweitzer K, Sharma S. Ophthaproblem: Can you identify this condition? Retrobulbar hemorrhage. Can Fam Physician. 2009 Jun;55(6):605, 607

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