Lateral Canthotomy Procedure

Lateral canthotomy (± cantholysis)

Lateral canthotomy with cantholysis is a time‑critical, sight‑saving emergency procedure to decompress the orbit in orbital compartment syndrome (for example, retrobulbar haemorrhage or severe orbital oedema).

It rapidly reduces orbital and intraocular pressure (IOP), relieves tension on the optic nerve and retinal circulation, and can prevent irreversible visual loss. This is a HALO‑level ED invasive procedure - follow local invasive‑procedure governance, checklist and DOPS/logbook recording (RCEM).

Clinical context and rationale

Orbital compartment syndrome occurs when a non‑expandable bony orbit is acutely filled by blood or swelling, compressing the globe and optic nerve. Compression can cause rapid, irreversible vision loss unless promptly relieved.

Lateral canthotomy (skin incision at the lateral canthus) and inferior cantholysis (division of the inferior limb of the lateral canthal tendon) create an anterior “window” that allows orbital contents to prolapse anteriorly and reduces intraorbital pressure. If needed, the superior crus can also be divided.

Indications - act without delay when vision is threatened

Proceed emergently when there is clinical evidence of orbital compartment syndrome with threat to vision. Typical triggers include:

• Progressive visual loss or sudden decrease in vision thought to be due to orbital compression.
• Tense proptosis with a hard globe.
• Markedly raised IOP (pragmatic threshold commonly used: ≥40 mmHg); do not delay treatment to obtain a reading if optic function is...