LRH · EMERGENCY DEPARTMENT

Lateral Canthotomy & Cantholysis

INDICATIONOrbital compartment syndrome (usually retrobulbar hematoma after trauma) — tense proptotic eye plus any of: RAPD, visual acuity worse than 6/18 (20/60), IOP ≥40 mmHg, ophthalmoplegia. 60–90 min critical ischemia time for optic nerve/retina — treat on clinical grounds, don't wait for CT. Only contraindication: suspected globe rupture.

EQUIPMENT
TRAUMA CART · DRAWER 6 · CANTHOTOMY KIT
This poster is the kit wrapper — zip-lock inside, folded behind the drawer label. Re-wrap it when you restock.
IN THE KIT — 6 ITEMS, ZIP-LOCK
  • 3 mL syringe — for the lidocaine
  • Needle to draw (blunt or 18 g)
  • Needle to inject (25–27 g)
  • Mosquito clamp — the 1-minute crush
  • Toothed forceps
  • Blunt-tipped iris scissors
ALSO NEEDED — NOT IN THE KIT
  • Lidocaine with epinephrine — from the medication drawer
  • Sterile saline for irrigation — never chlorhexidine/alcohol near the eye
  • Topical anesthetic drops
  • Tonometer (iCare/Tono-Pen) if available
  • Aftercare: antibiotic ointment; clean polystyrene cup, trimmed as a transport cover
KEY NUMBERS
≥40
IOP TRIGGER, MMHG
<6/18
VA TRIGGER
60–90
MIN ISCHEMIA WINDOW
~1 min
CLAMP TIME
1–2 cm
INCISION LENGTH
INFERIOR
CRUS TO CUT
FIG 1 · CANTHOTOMY + INFERIOR CANTHOLYSIS (RIGHT EYE)
STEPS
  1. Prepare: analgesia/sedation as needed, topical anesthetic drops, irrigate with saline.
  2. Infiltrate lidocaine + epinephrine at the lateral canthus toward the orbital rim — needle always pointing away from the globe.
  3. Crush: clamp the lateral canthus horizontally out to the rim for ~1 minute to devascularize the line.
  4. Canthotomy: cut along the crushed line — 1–2 cm horizontally from the lateral canthal angle to the orbital rim, exposing the canthal tendon.
  5. Cantholysis (the therapeutic step): grasp the lower lid at the lateral lash line with toothed forceps, pull up and out; strum the inferior crus with closed scissor tips (bowstring/“guitar string” feel); aim scissors toward the ipsilateral earlobe and cut it.
  6. Endpoint: tendon firmness lost, lower lid swings freely and is readily evertable, yellow orbital fat visible, globe softens, IOP falls. Re-assess the eye.
  7. Still tight? Re-explore and complete the inferior release in stages; avoid the superior crus unless forced.
  8. After: no eye pad — leave exposed for repeat exams (trimmed polystyrene cup for transport), antibiotic ointment, serial pupil/IOP checks.
  9. Disposition: CT and urgent ophthalmology consult.
Commonest pitfall: cutting skin only, not actually releasing the inferior canthal tendon. Most serious complication: iatrogenic globe injury — direct every instrument away from the globe.