Tag Archives: lateral canthotomy

Lateral Canthotomy

Posted on by

Lateral  Canthotomy – A Medical Student Clinical Pearl

Scott Clarke

Med III, Class of 2022

Dalhousie Medical School New Brunswick (DMNB)

Reviewed by Dr. Fraser MacKay

Copyedited by Dr. Mandy Peach

 

Case:

You are a clinical clerk working your first shift in a busy emergency department when you hear overhead those heart stopping, adrenaline pumping words: “Trauma team activation, room 24”. You arrive to find an unconscious 45 year old male. Report from the paramedics tells you there was a workplace accident whereby a tree had fallen and struck the patient in the face. The team works swiftly and efficiently to secure an airway and stabilize his vitals. From the team leader, your role is to perform a brief neurological exam.

Despite heavy sedation and swelling in the face, you are able to identify significant proptosis of his left eye. His right pupil is reactive to light but you notice his left responds significantly less and there is a positive relative afferent pupillary defect (RAPD). You relay your findings to the team lead and suggest an urgent CT scan of the head.

 

Before departing for CT your attending asks you – what diagnosis are you concerned for? What clinical findings support this diagnosis?

Orbital Compartment Syndrome1

Vision threatening condition where intraocular pressure (IOP) exceeds 40 mmHg.

Clues on exam:

  • Impaired extraocular movements (from a retrobulbar hematoma)
  • Decreased visual acuity
  • RAPD
  • Blown Pupil

Your attending agrees there is concern for orbital compartment syndrome and ophthalmology should be urgently paged – do you wait for CT to confirm retrobulbar hematoma?

No – You quickly grab a tono-pen and measure the intraocular pressure to be 50mmHg. In order to save this patient’s vision, a lateral canthotomy is immediately performed in an attempt to temporarily release pressure before definitive hematoma evacuation can occur.

Procedural Overview:

Equipment:

  1. Tono-pen
  2. Hemostat
  3. Local anesthesia
  4. Curved iris scissors (or scalpel)

Anatomy review:

The globe of the eye is held firmly in place by the strong tarsal plates and the medial and lateral canthal ligaments (Figure 2). By dividing the lateral canthus (inferior limb or both inferior and superior limbs), the globe has room to expand which can greatly reduce pressure3.

Figure 2: Anatomy of the components holding the globe of the eye4.

Procedure5:

  1. Clean the lateral portion of the eye using chlorhexidine or a similar solution.
  2. Inject 2-3cc of 1% lidocaine with 1:100,000 epinephrine into the site of the lateral canthus primarily for hemostasis
  3. Insert the hemostat into the lateral portion of the eye and crush the lateral canthus. Hold this for 30-45 seconds. This will devascularize the tissue resulting in further reduction in bleeding.
  4. Using the curved iris scissors (or scalpel), cut the lateral canthus to the rim of the globe, ~1-2cm at a slight downward angle.
  5. The inferior limb of the lateral canthal ligament will be able to be palpated and resembles a guitar string. This should be divided as well.
  6. If significant intraocular pressure remains, divide the superior limb of the lateral canthal ligament as well.
  7. Reassess ocular pressure.

 

Once the procedure is completed you wait 5 minutes and reassess the intraocular pressure. You notice that it has gone from 50mmHg to 38mmHg. The patient is sent for CT head which confirms a retrobulbar hematoma.

You follow up with the patient during his hospital stay and discover his vision eventually returns to his normal pre-injury.

 

Keys to remember6:

Indications include trauma patients with:
– Proptosis
– Impaired ocular movements
– Elevated Intraocular pressure, usually >40mmHg
– Decreased visual acuity
– RAPD

Ideally performed within 60-120 min of features of ischemia to the optic nerve1.

Absolute contraindication:
– Globe rupture

Medical treatment can also be initiated with the goal to help decrease intraocular pressure 1:

  • mannitol
  • acetazolamide
  • pilocarpine
  • timolol

See below for video of a lateral canthotomy on an actual patient (viewer discretion advised):

References

  1. Helman, A. Swaminathan, A. Austin, E. Strayer, R. Long, B, McLaren, J. Brindley, P. EM Quick Hits 24 – Lateral Canthotomy, Cannabis Poisoning, Hyperthermia, Malignant Otitis Externa, BBB in Occlusion MI, Prone CPR. Emergency Medicine Cases. December, 2020. https://emergencymedicinecases.com/em-quick-hits-december-2020/. Accessed [May 5, 2021].
  2. Retrobulbar Hematoma from Warfarin Toxicity and the Limitations of Bedside Ocular Sonography – The Western Journal of Emergency Medicine. https://westjem.com/videos/retrobulbar-hematoma-from-warfarin-toxicity-and-the-limitations-of-bedside-ocular-sonography.html. Accessed March 29, 2021.
  3. Amer E, El-Rahman Abbas A. Ocular Compartment Syndrome and Lateral Canthotomy Procedure. J Emerg Med. 2019;56(3):294-297. doi:10.1016/j.jemermed.2018.12.019
  4. Chan D, Sokoya M, Ducic Y. Repair of the Malpositioned Lower Lid. 2017. doi:10.1055/s-0037-1608711
  5. How to do Lateral Canthotomy – Eye Disorders – Merck Manuals Professional Edition. https://www.merckmanuals.com/en-ca/professional/eye-disorders/how-to-do-eye-procedures/how-to-do-lateral-canthotomy. Accessed March 29, 2021.
  6. Lateral Canthotomy – YouTube. https://www.youtube.com/watch?v=Qs5Smx-cxbo. Accessed March 29, 2021.
Continue Reading