Differentiation From Other Ocular Pathology

Other ocular processes may appear similar to RD on sonography, especially posterior vitreous detachment (PVD) and vitreous hemorrhage (VH). PVD may also appear as a hyperechoic linear density that has been lifted off the posterior globe; however, it typically appears as a thinner and smoother structure compared to RD. VH typically appears as nonlayering, low-level echoes within the vitreous body that are unattached to periphery of the globe (see image 4).

Because it can be difficult even for the expert ocular sonographer to differentiate these diagnoses from RD, we recommend prompt follow-up in any case with equivocal findings, especially when clinical features (e.g., photopsia) suggest RD.

Other findings such as retinal breaks or tears—which, as already addressed, are often the inciting event leading to RD—may be seen with ultrasound and are visible as small, echodense tufts elevated off the fundus.⁸ Given their small size, however, these structures typically require specialized ophthalmologic transducers for visualization. Thus, we do not believe this diagnosis should be considered within the scope of emergency sonography.

Discussion

Ocular ultrasound is emerging as a promising technique to diagnose RD. Sonography is especially helpful in cases where an adequate eye exam is impossible, or when the emergency physician does not have the luxury of time or expertise to perform a thorough, dilated fundoscopic exam.

If RD is identified, the patient should be referred to an ophthalmologist on an emergent basis, ideally within 24 hours. Because the sensitivity of this technique in the hands of emergency physicians using general-purpose portable ultrasound machines has yet to be determined, we recommend that any cases with high-risk clinical features, such as the presence of flashes of light or vision loss, also be referred on an urgent basis regardless of sonographic findings.

With this simple guide to ocular ultrasound, we hope more physicians will learn and incorporate ultrasound into their evaluation of ocular complaints in the emergency setting. We believe that ocular ultrasound is fast, safe, and easy to teach and learn. We hope you will remember to pick up the ultrasound probe for each CASE of potential retinal detachment you encounter.

Contributors

Dr. Teismann and Dr. Shah are both ultrasound fellows in the department of emergency medicine at Highland General Hospital in Oakland, Calif. Dr. Nagdev is the director of emergency ultrasound at Highland General Hospital’s department of emergency medicine. Medical Editor Dr. Robert C. Solomon is an attending emergency physician at Trinity Health System in Steubenville, Ohio, and clinical assistant professor of emergency medicine at the West Virginia School of Osteopathic Medicine, Lewisburg.