Pitfalls in the Use of Ocular Ultrasound for Evaluation of Acute Vision Loss

Abstract

Background

Retinal detachment is a true medical emergency. It is a time-critical, vision-threatening disease often first evaluated in the Emergency Department (ED). Diagnosis can be extremely challenging and confused with other ocular pathology. Several entities can mimic retinal detachment, including posterior vitreous detachment and vitreous hemorrhage. Ocular ultrasound can assist the emergency physician in evaluating intraocular pathology, and it is especially useful in situations where fundoscopic examination is technically difficult or impossible. Accurate and rapid diagnosis of retinal detachment can lead to urgent consultation and increase the likelihood of timely vision-sparing treatment.

Objectives

This case demonstrates both the utility of ocular ultrasound in the accurate and timely diagnosis of retinal detachment and potential pitfalls in the evaluation of intraocular pathology in the ED.

Case Report

A 38-year-old woman presented with acute onset of bilateral visual loss that was concerning for retinal detachment. Rapid evaluation of the intraocular space was performed using bedside ocular ultrasound. Bedside ocular ultrasound correctly diagnosed retinal detachment in the right eye. Posterior vitreous detachment in the left eye was incorrectly diagnosed as retinal detachment.

Conclusion

This case illustrates the importance of bedside ocular ultrasound and highlights some of the pitfalls that can occur when evaluating for retinal detachment. Following is a discussion regarding methods to distinguish retinal detachment from vitreous hemorrhage and posterior vitreous detachment.

Introduction

Eye complaints are common in the Emergency Department (ED), composing approximately 2% of all visits (1). Evaluation for retinal detachments in patients with acute visual change are of particular importance, as immediate identification and treatment of this disease is imperative to prevent deterioration to permanent, complete visual loss. Without treatment, all cases of retinal detachments will spread and involve the macula, causing blindness (1).

The retina is composed of two layers: the neuronal layer, and the supportive choroid layer. Detachment occurs when these two layers separate (2). Patients with retinal detachment often complain of acute onset of floaters or flashes of light in their visual field. This is often followed by acute painless visual loss beginning peripherally and progressing to the central visual field, commonly described as a curtain being pulled over the field of vision, or a sensation of seeing cobwebs (1).

Diagnosis of retinal detachment has been traditionally performed via fundoscopic examination. However, this type of examination is technically challenging, and cannot completely rule out retinal detachment. Additionally, fundoscopic examination may be impossible in certain situations where visualization of the posterior surface of the eye is challenging, such as in vitreous hemorrhage or dense cataracts. Ultrasound has been used by ophthalmologists to evaluate the orbits for over 50 years; however, it has only gained traction in the hands of emergency physicians in the past decade (3).

Ocular ultrasound has been shown to be quick, accessible, and accurate for the assessment of ocular pathology when performed by emergency physicians 4, 5. In particular, ultrasound is highly sensitive in the detection of retinal detachment in the ED (6). The globe is an amazingly facile organ to evaluate with ultrasound. To perform this examination, linear 7.5- to 10-MHz probes are ideal for taking a detailed look at the orbit. With the eyelids closed, a generous amount of conducting gel is applied to the lid (7). For patient comfort and to facilitate clean-up, a transparent dressing can be placed on the lid before applying gel (8). The probe is then placed gently perpendicular to the orbit while fanning cephalad to caudad (7). For further instruction on the use of sonogram to perform ocular ultrasound, please see http://emedicine.medscape.com/article/1401982-overview (7). We present a case that demonstrates both the utility of, and the pitfalls in, the use of ocular ultrasound in the ED.