Lateral Canthotomy Summary

Indications

  • Orbital compartment syndrome (OCS)
  • Rapid, progressive vision loss
  • Increased intraocular pressure
  • Decreased extraocular motility and pain

Contraindications

  • Suspected globe rupture
  • Irregular pupil
  • Hyphema
  • Herniated iris tissue
  • Shallow cornea
  • Leak of aqueous humor

Procedure Steps

  • Position patient supine
  • Prepare skin with antiseptic
  • Inject local anesthetic
  • Crush tissue with hemostat
  • Perform canthotomy
  • Perform cantholysis (inferior crus)

Complications

  • Mechanical damage to eye structures
  • Hemorrhage
  • Infection

Aftercare

  • Apply antibiotic ointment
  • Cover with sterile dressing
  • Consider steroids for vision loss
  • Manage elevated intraocular pressure

Lateral Canthotomy

Emergency procedure for orbital compartment syndrome

Introduction

Lateral canthotomy, the emergency treatment for orbital compartment syndrome, is the surgical exposure of the lateral canthal tendon. Cantholysis is canthotomy plus incision of the inferior branch (crus) of the tendon.

Anatomical Background

The lateral canthal tendon has two branches: a superior and an inferior. Cutting one, or both, loosens the eyelids and allows the globe to expand out of the orbit and thus relieve intraorbital pressure on the eye.

Indications

Orbital Compartment Syndrome (OCS)

OCS is an ophthalmologic emergency, which manifests with rapid, progressive vision loss, increased intraocular pressure, decreased extraocular motility and pain, in a patient with recent eye/orbital trauma or surgery.

Pathophysiology

Blunt facial trauma may cause retrobulbar haematoma or severe oedema surrounding the eyeball, either of which can increase intraorbital pressure. Because the eye is constrained by the lids and the orbit, increased intraorbital pressure can cause intraocular pressure to rise rapidly and compress the optic nerve and its vascular supply. Untreated, this increased pressure causes permanent vision loss.

Time Sensitivity

Speed of diagnosis of OCS and of execution of the canthotomy or cantholysis procedure are important to minimise the duration of retinal ischaemia. Ophthalmologic consultation should be requested but should not delay the procedure. Because the diagnosis of OCS is purely clinical, the procedure also should not be delayed for imaging studies.

Contraindications

Absolute Contraindication

Suspected globe rupture with any of the following signs:

  • Irregular pupil
  • Hyphema
  • Herniated iris tissue
  • Shallow cornea
  • Leak of aqueous humor

Complications

Mechanical Damage

  • Damage to lateral rectus muscle
  • Damage to lacrimal gland
  • Damage to lacrimal artery
  • Eyelid damage

Other Complications

  • Hemorrhage
  • Infection

Procedure

Pain Management

This procedure is painful. A conscious, confused, or uncooperative patient may require regional nerve block, sedation, or restraint to prevent motion that could result in damage to the eyeball during the procedure. Children may require general anaesthesia in the operating room.

Step-by-Step Procedure

  1. Positioning: Position the patient supine on the bed and stabilise the patient's head and eyelids.
  2. Preparation: Prepare the skin with an antiseptic agent such as povidone iodine or chlorhexidine; do not allow the antiseptic to enter the eye. Drape the area.
  3. Anesthesia: Inject 1 or 2 mL of local anaesthetic containing epinephrine into the lateral canthal incision site.
  4. Tissue Crushing: Use a needle driver or haemostat to crush the tissue from the lateral canthus to the rim of the orbit, for about 20 sec to 2 min. Crushing this tissue helps minimise bleeding and makes it easier to see where to cut when there is extensive traumatic oedema.
  5. Canthotomy: Use iris scissors to cut from the lateral canthus to the rim of the orbit, about 1 to 2 cm.
  6. Cantholysis: Cut the inferior and sometimes both crus of the lateral canthal ligament.
    • Most experts recommend starting with the inferior crus. Lift the inferior portion of the lateral eyelid. With the scissors pointing away from the globe, identify and cut the inferior crus. "Strumming" with the scissors may help identify the inferior crus. If the tendon is still intact, you will feel a twanging like a plucked string. When cutting the inferior crus, aim inferoposteriorly toward the lateral rim to avoid injuring the levator muscle, lacrimal gland, and lacrimal artery, which are located superiorly.
    • Next, some experts recommend routinely cutting the superior crus. Others recommend reassessing for relief of OCS (e.g. by measuring intraocular pressure) and cutting the superior crus only if OCS persists. To cut the superior crus, lift and expose the underside of the lateral upper eyelid. Check whether the superior crus tendon has been cut by strumming across it with the scissors. If the tendon is still intact, cut it. Cutting the tendon loosens the eyelid and relieves pressure on the eye even more.

Aftercare

Immediate Aftercare

  • Because the patient can't blink to lubricate the cornea, apply an antibiotic ointment to the eye and cover it with a sterile dressing.
  • Lateral canthotomy incisions are not sutured at the time of the canthotomy and often heal without significant scarring.
  • Patients with severe injuries should be hospitalised.

Medical Management

  • Methylprednisolone (i.e. 250 mg IM/IV q 6 h) for 3 days should be considered for inpatients with progressive vision loss.
  • If intraocular pressure remains elevated, topical therapy (e.g. timolol 0.5%, brimonidine 0.2%, or dorzolamide 2% eye drops) or systemic therapy (e.g. acetazolamide immediate-release 500 mg po, or mannitol 1-2 mg/kg IV over 45 min) should be considered.

Patient Instructions

Patients should avoid straining and apply ice packs for several days following canthotomy.

Comparison: Canthotomy vs Cantholysis

Procedure Definition Purpose Complexity
Lateral Canthotomy Surgical exposure of the lateral canthal tendon Initial step to access the tendon Less complex
Lateral Cantholysis Canthotomy plus incision of the inferior branch of the tendon Releases pressure by loosening eyelids More complex