Probe Selection A high frequency (7-12 MHz) linear array transducer should be used to visualize superficial structures (Image 1).

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1 ! Teresa S. Wu, MD, FACEP Director, Emergency Ultrasound Program & Fellowships Co-Director, Women s Imaging Fellowship Maricopa Medical Center Associate Professor, Emergency Medicine Director, Simulation Curriculum University of Arizona, College of Medicine-Phoenix Background & Indications The eye is a fluid filled structure and is therefore an excellent organ to evaluate via ultrasound. Bedside ocular ultrasound can be used to detect vitreous hemorrhage, retinal detachments, lens dislocations, globe rupture, intraocular foreign bodies, cataracts, retrobulbar hematomas, and dilated optic nerve sheaths. Ocular ultrasound is safe and provides valuable information within minutes. Images of the globe and the retrobulbar space can be obtained rapidly without subjecting the patient to any pain, radiation, or risks of transport out of the ED. Ocular ultrasound can be used to augment physical exam findings, and is especially useful in patients with eyelid edema or in patients who are unable to cooperate with a good fundoscopic examination. Probe Selection A high frequency (7-12 MHz) linear array transducer should be used to visualize superficial structures (Image 1). Image 1: High frequency linear array transducer.! The images and pictures in this handout are copyright protected. Please do not copy or distribute them without written consent from the author. "

2 Page 2 of 9 Performing the Scan Place the patient in a position of comfort. Acoustic gel can be placed directly over the patient s closed eyelid (Image 2). Sterile gel should be used to perform the scan if no barrier is being used between the probe, gel, and patient s eyelid. Conversely, skin dressing, such as Tegaderm or an Op Site, can be placed over the closed eyelid first, and then the gel can be applied over the dressing (Image 3). Place the probe in a transverse fashion across the closed eyelid with the indicator marker pointing towards the patient s right (Image 4). Consider preforming a scan of the contralateral eye first to become familiar with the patient s normal anatomy. When eyes close, the globe naturally rotates superiorly and posteriorly. Have the patient look straight ahead through their closed, relaxed eyelids. Image 2: Acoustic gel placed directly on the patient s closed eyelid during an ocular ultrasound.

3 Page 3 of 9 Image 3: Application of a medical dressing over the eye to prevent accidental exposure of the eye to ultrasound gel. Place the medical dressing over the closed eyelid and then apply the ultrasound gel over the dressing. Image 4: Performing an ocular ultrasound. A medical dressing is applied to protect the eye. Note that the probe indicator is pointing towards the patient s right side. Adjust the depth and gain so that you can visualize the anterior chamber, iris, lens, posterior chamber, and the retina/choroidal layers (Image 5). To evaluate for abnormalities of the posterior globe (e.g. vitreous hemorrhage), it is important to turn up the farfield gain. Ask the patient to look up, down, left, and right during the scan to help with visualization of the entire globe. Dynamic movement of the eye will often enhance visualization of subtle vitreous hemorrhages and retinal detachments. If the patient has a retinal detachment, you will see a hyperechoic thin ribbon of retina separated from the posterior globe.

4 Page 4 of 9 Look for hyperechoic spots, lines, or clusters of material in the posterior chamber suggestive of a vitreous hemorrhage. Determine if the hyperechoic lens has been dislocated posteriorly or anteriorly from in between the irises. Assess for the presence of any foreign bodies or periorbital abscesses or masses. Increase the depth and adjust the exam settings to evaluate the optic nerve sheath or retrobulbar space. In adults, the optic nerve should be < 5 mm in diameter when measured 3 mm behind the globe. If the patient has a retrobulbar hematoma, it will appear as a hypoechoic collection of blood just posterior to the globe. Obtain a good look at the pupil to determine its size and reactivity. A light can be directed into the contralateral eye to check for a consensual pupillary response. Image 5: Ultrasound of a normal eye (AC=anterior chamber) and corresponding ocular anatomy.

5 Page 5 of 9 Normal Sonographic Anatomy Image 6: Ultrasound of the normal eye (AC=anterior chamber) and corresponding ocular anatomy. Image 7: Measuring the optic nerve (D1: 3 mm behind the posterior globe; D2: optic nerve diameter). Image 8: Evaluating pupil size and reactivity with bedside ultrasound.

6 Page 6 of 9 Notable Pathology Image 9: Ocular ultrasound demonstrating retinal detachment. Image 10: Ocular ultrasound demonstrating vitreous hemorrhage. Image 11: Ocular ultrasound demonstrating lens dislocation.

7 Page 7 of 9 Image 12: Ocular ultrasound demonstrating globe rupture. Image 13: Ocular ultrasound demonstrating an intraocular foreign body (arrow). Image 14: Ocular ultrasound demonstrating a periorbital abscess.

8 Page 8 of 9 Image 15: Ocular ultrasound demonstrating a retrobulbar hematoma. Image 16: Dilated optic nerve from intracranial hemorrhage (6.9 mm at 3 mm behind the globe). Image 17: Ocular ultrasound demonstrating papilledema.

9 Page 9 of 9 Pearls & Pitfalls in Performing a Bedside Ocular Ultrasound Use a high frequency linear array transducer with ocular presets. Place the probe in a transverse fashion to scan through the axial plane of the eye. The indicator marker on the probe should be directed towards the patient s right side. Improve your acoustic window by using a generous amount of gel or an acoustic standoff pad. Limit the amount of pressure applied to the eyelid and globe. If a globe rupture is suspected, apply a thick layer of gel on top of the patient s eyelid and gently float the probe over the gel. Do not place direct pressure onto the eyelid with the probe. Have the patient look in all four quadrants during the scan to maximize visualization of the entire globe and the periphery. Many retinal detachments will have an associated vitreous hemorrhage. Identify the anchoring points of the retinal detachment by having the patient alter their gaze during your scan. Subtle ocular findings can be enhanced by increasing the overall gain of the scan. Consider performing a scan of the patient s contralateral eye to become familiar with his/her normal sonographic anatomy. For more bedside ultrasound tips and tricks, check out the ultrasound app SonoSupport. Happy