How to perform a lateral canthotomy

Brandon Pham, M.D., Benjamin Lin, M.D., Randal Pham, M.D.

Overview

Orbital compartment syndrome is an ophthalmic emergency that can lead to rapid blindness if not promptly diagnosed and managed. Lateral canthotomy and cantholysis is the treatment of choice and involves surgically exposing the lateral canthal tendon and its inferior crus to relieve intraorbital pressure.

Illustration by Lauren Chen

Anatomy

The medial canthal ligament and lateral canthal ligament both keep the eye within the orbit. The lateral canthal tendon, which is the focus of this guide, has a superior crus (branch) and an inferior crus. Cutting the inferior crus relieves intraorbital pressure by loosening the inferior eyelid and allowing the globe to expand out of the orbit. Sometimes, the superior crus is also cut to further relieve intraorbital pressure.

Indications

Lateral canthotomy should be performed as acute management for orbital compartment syndrome, which presents with increased intraocular pressure (IOP) and impaired extraocular motility. Typically, this syndrome occurs within the context of recent orbital trauma or eye surgery. Indications for immediate canthotomy include sudden vision loss or relative afferent pupillary defect in the setting of retrobulbar hemorrhage with proptosis and IOP greater than 40 mm Hg.

Contraindications

Lateral canthotomy should not be performed in patients with suspected open globe, which may present with a corneal laceration, positive Seidel sign, hyphema, irregularly shaped pupil, herniated uveal tissue, and/or shallow anterior chamber.

Equipment

Required equipment for lateral canthotomy and cantholysis includes:

• Sterile gloves, gauze, face shield, gown, and drapes
• Antiseptic solution (chlorhexidine or Betadine)
• Local anesthetic (lidocaine 1-2% with epinephrine)
• Syringe (3 mL) with small injection needles (27- to 30-gauge)
• Irrigation fluid (normal saline or water)
• Needle driver or straight hemostat (battery cautery if available)
• Sterile iris or suture scissors
• Forceps (at least 0.3 mm teeth)
• Antibiotic ointment (erythromycin 5% or bacitracin)

Patient Positioning

Patients should be placed supine with the head of the bed slightly elevated at roughly 10-20º, with their eyelids and head stabilized to prevent iatrogenic injury during the procedure.

Procedure Instructions

1. Begin by grossly inspecting the globe and roughly estimating visual acuity.
2. Clean and irrigate lateral canthus area. Prepare the area with antiseptic chlorhexidine or Betadine and drape.
3. Inject 1-2 mL of local anesthetic with epinephrine into planned incision site. While injecting, aim the tip of the needle AWAY from the globe.
4. Using a needle driver/hemostat, approximate the path of your incision from the lateral canthus to the rim of the orbit and lock the hemostat in place for about 20 seconds to 1 minute to crush the tissue, which helps with hemostasis. While placing the instrument, you should be able to feel the inferior jaw of the needle driver/hemostat on the bony orbital rim. After crushing the tissue, remove the needle driver/hemostat.
5. To perform the canthotomy, cut from the lateral canthus to the rim of the orbit using iris scissors, following the path of crushed tissue made in the previous step. The full length of incision should be about 1 to 2 cm. Note: Maximum length of cut should not be more than 2 cm because the temporal branch of the facial nerve passes through this area. The temporal branch is a single nerve with no anastomosis.
6. Lift the lateral portion of the inferior eyelid to expose the lateral canthal tendon. To perform cantholysis, identify and cut the inferior crus of the lateral canthal ligament. Ensure that your scissors are pointing away from the globe during the incision.

Illustrated images by Lauren Chen 

Tips and Tricks

Identifying the inferior crus of the lateral canthal tendon can sometimes be tricky. Use scissors to “strum” the area to feel for the inferior crus. If you feel tension (like a plucked string), the tendon is still intact and should be cut.

During cantholysis, cut inferoposteriorly toward the lateral rim to prevent injury to nearby structures superiorly, such as the levator muscle, lacrimal artery, and lacrimal gland.

In some situations, the superior crus may also be cut to further relieve intraorbital pressure. To do so, lift and expose the underside of the lateral upper eyelid and make the incision superoposteriorly.

Follow-up

Lateral canthotomy incisions typically do not need to be sutured and heal on their own with minimal scarring. Patients cannot blink to lubricate the cornea after canthotomy. Therefore, make sure to apply an antibiotic ointment (e.g. erythromycin 5%) to the eye and cover with a sterile dressing to prevent infection. Ice packs may be used in the days following canthotomy to reduce pain and inflammation.