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Pearls & Pitfalls for Diagnosing a Globe Rupture on Bedside US
1. Globe ruptures are true ophthalmologic emergencies and often times, the diagnosis can be difficult to make based on exam findings alone.
2. The physical exam is often hindered by orbital edema or limited by patient discomfort and poor cooperation.
3. In blunt trauma, the ruptures are most common where the intraocular muscles insert on the sclera. The globe becomes thinner at those junctures and traction from blunt mechanisms can lead to small tears.
4. When you suspect that your patient has a globe rupture, care must be taken to minimize the amount of pressure placed on the globe. Direct pressure on the orbit can cause further extrusion of intraocular contents.
5. Bedside ultrasound, if used with care, can aid in rapid diagnosis of ocular conditions without causing harm.
6. Use the high frequency linear array transducer (7-10 MHz).
7. Apply a copious amount of water-soluble gel over the patient’s eyelid or use an acoustic stand off pad to enhance visualization of the globe and intraocular contents.
8. Float the probe in a transverse fashion over the gel. Take special care to ensure that pressure is not placed on the closed eyelid. Also avoid scanning the eye continuously for more than 60 seconds at a time.
9. Attempt to visualize the anterior chamber, the lens, the posterior chamber/vitreous body, the retina, the circular borders of the orbit, and the retrobulbar space.
10. Findings of a globe rupture include a flattened anterior chamber, abnormal lens positioning or lie, scleral buckling, an irregularly shaped or flattened vitreous body, or evidence of blood filling the posterior chamber mixed with vitreous humor.
11. Bedside ultrasound findings should be correlated with the physical exam and computed tomography findings if the diagnosis is uncertain.
12. The normal, contralateral eye can be used for comparison when subtle sonographic findings are in question.
13. Practice! Practice! Practice! With bedside ultrasound, there is no substitute for experience. The more scans you do, the better you will be able to differentiate abnormal from normal, even when you may not be sure exactly what the abnormality is.
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