A 24-year-old male presents to the ED late Saturday night after leaving the local watering hole. One may say he had a few too many, but according to the patient, he was just “minding his own business” when he was “sucker punched” in the right eye. The patient now is unable to see out of his right eye. On exam, you find severe periorbital edema, decreased visual acuity, and an afferent pupillary defect (Marcus-Gunn) in the right eye. A CT of the head and maxillofacial bones is performed, which is negative for intracranial hemorrhage or retrobulbar hematoma. After fluorescein staining, you check the intraocular pressure only to find it to be 45 mm Hg. As an emergency physician, you begin to have flight of ideas: Is there any indication to perform a lateral canthotomy without a retrobulbar hematoma? Visualization to perform the procedure is a problem due to edema. Is there a trick to improve visualization and prevent iatrogenic globe rupture?
Indications for Lateral Canthotomy
Emergency physicians are commonly taught that the indication for lateral canthotomy and inferior cantholysis is acute trauma with a retrobulbar hematoma causing an increase in the intraocular pressure. While this is a classic example, and an appropriate indication to dust off the iris scissors, it is far from the only reason to perform this potentially vision-saving procedure.1–5 Orbital compartment syndrome (OCS) is an ophthalmologic emergency that, unfortunately, is on the rise due to increasing use of antiplatelet and anticoagulant medications.1 In turn, emergency physicians across the country are going to be called upon more frequently to perform a decompression of the orbit in a timely fashion. Studies suggest permanent vision loss can be seen in as little as 30 minutes once the intraocular pressure (IOP) threshold is met.2 Prompt recognition and familiarity with the indications to perform a lateral canthotomy are crucial to improve the chances of preserving the patient’s vision. This begets two questions: When do you perform a lateral canthotomy? And does releasing the inferior tendon from the bony orbit improve outcomes?
When discussing outcomes of a lateral canthotomy, most studies look at intraocular pressure as the primary outcome of the trial. With regard to IOP, a 2009 article by Lima et al showed a greater reduction in intraocular pressure was achieved by lateral canthotomy and cantholysis (30.4 mm Hg) compared with canthotomy (14.2 mm Hg) or cantholysis (19.2 mm Hg) alone, answering the age-old question of whether inferior cantholysis is helpful.1