Welcome to another ultrasound-based case, part of the “Ultrasound For The Win!” (#US4TW) Case Series. In this case series, we focus on a real clinical case where bedside ultrasound changed the management or aided in the diagnosis. In this case, a 76-year-old man presents with sudden-onset right-sided vision loss.
Case Presentation
A 76-year-old man with history of hypertension presents to the emergency department (ED) with a complaint of 5 hours of sudden-onset right-sided vision loss. He notes seeing flashes of light in the periphery of his field of vision followed by several “floaters”. He denies any trauma, headache, or pain. On physical examination, he appears well and is in no acute distress. Neurologic examination is grossly unremarkable. Pupils are 3 mm, round, and reactive to light bilaterally. Visual acuity is 20/20 OS, and 20/100 OD. Intraocular pressures are measured at 8 mm Hg bilaterally.
Vitals
BP 131/62 mmHg
P 78 bpm
RR 20 respirations/min
O2 99% room air
T 37.4 C
Differential Diagnosis
- Migraine
- Optic Neuropathy
- Posterior Vitreous Detachment
- Retinal Artery/Vein Occlusion
- Retinal Detachment
- Stroke/TIA
- Uveitis
Point-of-care Ultrasound
Figure 1. Retinal detachment of the affected eye
Figure 2. A retinal detachment is visualized (blue arrow). Also note the anterior chamber (AC) and vitreous chamber (VC)
Ultrasound Image Quality Assurance (QA)
The eye, being a superficial fluid-filled structure, is an optimal organ for diagnostic ultrasonography. Point-of-care ocular ultrasound is fairly straightforward; images are obtained using a high-frequency linear transducer with the “ocular” setting on the ultrasound machine, if available.
A generous amount of gel should be used over a closed eyelid, with or without a tegaderm. Both the affected and unaffected eye should be examined for comparison, with normal landmarks and anatomy noted (Figure 3).
Figure 3. Normal Ultrasound Anatomy of the Eye: From anterior (top of image) to posterior (bottom of image): Cornea (C), Anterior Chamber (AC), Lens (L), Vitreous Chamber (VC), Retina (blue arrow), Optic Nerve (ON).
A retinal detachment (RD) is a separation of the two layers of the retina, which invariably causes blindness if left untreated.1 On ultrasound, this appears as a bright hyperechoic wavy line within the vitreous chamber coming off the posterior aspect of the eye. Associated vitreous hemorrhage may also be visualized as hyperechoic strands within the vitreous chamber that move with eye movement, and has the appearance of clothes tumbling in a washing machine (The “Washing Machine Sign”).
It is especially important to optimize the gain, or brightness, with ocular studies. Generally, the gain is set slightly higher than usual to just the point of visualizing small echogenic material within the vitreous chamber. This avoids missing a potential subtle RD if the gain is set too low. With the ultrasound probe oriented transversely then longitudinally over the globe, the probe is fanned back and forth, spanning the entire globe. Finally, the patient should move their eye in all directions in order to fully evaluate the entire globe for pathology.
Common Pitfalls
- Inadequate gain. Gain, or brightness, that is set too low can miss subtle structures including a detached retinal flap. Gain that is too high can increase acoustic enhancement artifacts posteriorly, also with the risk of missing a retinal detachment.
- It can be normal to see artifacts within the vitreous chamber, which may appear as bright echogenic material; movement of the eye should cause artifacts to “disappear”. (Figures 4, 5)
Figure 4. Pitfall: Normal ocular ultrasound with artifact in the vitreous chamber
Figure 5. Artifacts can sometimes be mistaken for retinal detachment or other pathology
Ultrasound Fanatic Side Note: Ophthalmologists were among the first physicians to use ultrasound in their clinical practice. Ultrasound of the orbit has been described in the ophthalmology literature to aid in the diagnosis of retinal detachment as early as 1957 by Oksala and Lehtinen.2 Their use of A (Amplitude)-mode, visualized as a graph of spikes along an axis, differs from the more conventional B (Brightness)-mode, the series of 2D images that we currently use in the ED. For additional reading, please refer to History of Ophthalmic Ultrasound by Lizzi and Coleman.3
Disposition and Case Conclusion
Given the concerning finding of a retinal detachment, ophthalmology was consulted and confirmed the diagnosis of retinal detachment. The patient underwent definitive treatment and his visual acuity has been spared.
Retinal detachment affects 1 in 300 people, and remains a time-critical and vision-threatening diagnosis that emergency physicians (EP) must consider in patients presenting with ocular complaints.4 Patients presenting with RD typically complain of sudden-onset unilateral painless loss of vision or visual field deficits. They may describe “flashing lights”, “floaters”, or “spider webs” in their field of vision. If the macula is not detached, the goal is to undergo definitive treatment to spare the macula. Time to treatment is critical in these cases as the duration of macular detachment is inversely related to a patient’s ultimate visual acuity.5 Patients will often have good outcomes if treated promptly. Thus, a high-level of suspicion and ophthalmologic consultation with close follow-up is warranted for definitive care.
The vast range of ocular pathologies that present to the ED remains challenging for the EP to diagnose without a dedicated fundoscopic examination. Unfortunately, a physical examination including non-dilated direct fundoscopy is often inadequate, and has been shown to miss 38% of retinal pathologies that required intervention.6 The use of point-of-care ultrasound by the EP serves as a vital adjunct to clinical assessment in the time-critical diagnosis of intraocular diseases including retinal detachment. While seemingly an “advanced” ultrasound technique, the findings of RD are not subtle and can be easily identified, as was seen in this particular case. In fact, a prospective study by Shinar et al. found that EPs can accurately diagnose RD using bedside ultrasound with a sensitivity of 97% and specificity of 92%.7 Additionally, Blaivas et al. showed that 60 out of 61 intraocular diseases were accurately diagnosed by the EP with bedside ultrasound when using an ophthalmologists’ evaluation as the gold standard.8
The main indications for ocular ultrasound in the ED expand beyond looking for retinal detachment, and include assessing for vitreous hemorrhage, intraocular foreign bodies, lens dislocation, or to evaluate for signs of elevated intracranial pressure (Table 1). Note that the only absolute contraindication to ocular ultrasound is a suspected ruptured globe, in which case no pressure should be placed on the globe.
Table 1. Indications and Contraindications for Ocular Ultrasound in the Emergency Department
| Indications for Ocular Ultrasound |
|---|
| Acute vision changes or loss of vision |
| Orbital trauma (when globe rupture is not suspected) |
| Atraumatic eye pain |
| Elevated intracranial pressure |
| Intraocular foreign body |
| Contraindications to Ocular Ultrasound |
| Suspected globe rupture |
Take Home Points
- Retinal Detachment is a time-sensitive ophthalmologic emergency that invariably leads to blindness if left untreated. If there is suspicion of RD, ophthalmology consultation is warranted.
- While a dilated fundoscopic exam is typically required for diagnosis of RD, this is often not feasible or available in a busy ED or community setting.
- Emergency physicians can be highly accurate in the diagnosis of intraocular pathologies including RD with the aid of point-of-care ultrasound with 97% sensitivity and 92% specificity.
*Note: All identifying information and certain aspects of the case have been changed to maintain patient confidentiality and protected health information (PHI).
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