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7.05: Zone O3 – Mid Pupillary Inferior Orbit

YOUR ASSIGNMENT FOR THIS LESSON

✅ Step #1: Review all content below.

✅ Step #2: Image the O3 zone on your own with your ultrasond, and using the checklist provided on this page, check off all key structures to be identified in this location

TRANSDUCER POSITION AT O3

STANDARD O3 ORIENTATION:
LONGITUDINAL

Mid-pupillary line at the inferior margin of orbit Is the O3 position

QUICK TIP
  • Locate the bone of the orbital rim first to determine your optimal depth of imaging. 
  • Superior to the orbital rim will be the orbital fat and globe of the eye.
  • A hypoechoic structure superficial to this bone will be the orbicularis oculi muscle, and between this muscle and the bone will be the SOOF.
  • On occasion, inferior to the orbital rim and deep to the orbicularis oculi muscle, you can make out the superior aspect of the LLS muscle.

EXAMPLE OF IMAGE ACQUIRED AT O3

Standard image acquired at O3. Right O3 Position (Longitudinal | Left side is deep). See key below for lables.*

ANATOMICAL LEGEND FOR O3 LOCATION IN LONGITUDINAL

*Standard image acquired at O3 labeled with key anatomical structures.

DOPPLER IMAGES ACQUIRED AT O3 OF KEY VESSELS

Play Video
QUICK TIP
  • Like O2 in O3, you will likely be visualizing veins in this location. Over the orbicularis oculi muscle, you may identify superficial periorbital vessels. Deep to the obicularis oculi can in some patients identify the angular vein as it runs more lateral to its companion artery.
    • There is a lot of variability in the course of the angular vein, do not expect to always see it at O3, you may need to scan slightly inferior in the medial and lateral directions to detect it.

DO IT YOURSELF CHECKLIST

Structures to Identify on Ultrasound for O3

Once you have completed this checklist, mark this part of the lesson as complete.