Several dogmas are passed down from generation to generation in medicine, often with little scientific evidence to support them: Only use plain lidocaine on fingers; give steroids to patients with spinal cord injuries; don't give narcotics to patients with acute abdominal pain to avoid “masking” peritonitis. All of these were debunked after they were put to the test.
The caveat to ultrasound of the eye has always been that it should be avoided in patients with a known or suspected globe rupture because it may cause extrusion of the ruptured contents and worsen outcome. This dogma has rarely been questioned, but a recent case got me thinking about this theoretical concern.
I evaluated a young woman who had been beaten severely on her head and face and who had significant periorbital swelling. I was unable to open the eyelid to get more than a hint of a view of the globe because of swelling and the significant amount of pain that this attempt caused. A quick bedside ultrasound offered me a much better view of her eye (Image 1) and unmasked the ruptured globe that had been hidden under her severely swollen eyelid. We quickly terminated the ultrasound once this was found and contacted the ophthalmologist on call.
After an angry email from one of the ophthalmology faculty about my use of ultrasound, I began to consider the dogma that must be avoided in cases of suspected ruptured globe. Certainly, it makes sense that care should be taken to avoid placing any further pressure on the eye when this diagnosis is known or highly suspected. Trying to guess what is under a swollen eyelid is not an easy task, however, and we can't call our ophthalmologists every time a patient with facial trauma shows up in the ED. And how much pressure is exerted just in the sheer act of trying to open the swollen eyelid enough to see anything?
As with all dogma, hypothetical evidence is more common than scientific data about the damage caused by ultrasound of the eye. There is, in fact, a dearth of research about this for bedside ultrasound. An interesting piece from the Western Journal of Emergency Medicine looked at the change in intraocular pressure (IOP) associated with ocular ultrasound in healthy adults. Interestingly, they found that the change in IOP associated with ultrasound was less than the normal diurnal variation of the subjects and was less than the pressure generated by a simple physical exam. (West J Emerg Med 2015;16:263.)
Examining a traumatized eye behind a swollen eyelid is a challenge made easier by ultrasound. Discarding this advantage over minimally studied concerns about increasing IOP may be on par with avoiding ketamine in patients with potential head injury. In other words, it's another dogma that needs to be discarded.
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