Visualization of the optic disc is critical in the assessment of the patient with suspected papilledema and is the gold standard for evaluating for optic disc edema and papilledema. Fundoscopy may show optic disc hyperemia, retinal hemorrhages, distention of the retinal veins, loss of pulsations of the retinal veins, and optic disc elevation. Fundoscopy can be challenging to interpret because optic disc edema may be difficult to differentiate from other optic disc abnormalities such as pseudopapilledema, crowded optic disc morphology, and optic disc drusen. The direct ophthalmoscope
is commonly found in emergency departments (EDs), although limited training, uncertainty in interpreting results, and other time demands may lead to reluctance in performing the exam. The PanOptic ophthalmoscope is another instrument sometimes found in EDs. The direct ophthalmoscope has a 5° field of view, whereas the PanOptic ophthalmoscope has a 25° field of view. In a study of 36 emergency medicine residents, participants were significantly more likely to identify pathology using a PanOptic ophthalmoscope compared with a direct ophthalmoscope.¹ If the optic disc cannot be visualized by direct ophthalmoscopy and visualization of the optic disc is necessary, pupillary dilation may be considered. Pupillary dilation can be accomplished with short-acting mydriatic eye drops. Atropine should not be considered for diagnostic purposes because the effect on vision and pupillary dilation can last days to weeks. In patients with narrow angle anatomy, diagnostic pupillary dilation may precipitate an attack of angle closure glaucoma.

Nonmydriatic fundus camera photography is a tool that can increase the ability to visualize the optic disc and fundus without the need for pupillary dilation (Figure 51.1). Although some EDs have retinal cameras, most do not, although this may change with decreased cost and increased portability. Bruce et al demonstrated successful use of nonmydriatic ocular fundus photography by a nurse practitioner in the ED with high patient satisfaction with the technique. The median time
of image acquisition was 1.9 minutes.² Interpretation of images can be performed on-site by an experienced clinician or remotely by a tele-consultant.

Although most of the published studies enrolled few patients, ultrasound measurement of optic nerve sheath diameter (ONSD) and optic disc height (ODH) is potentially useful in screening for papilledema and increased ICP.³ To measure the ONSD, a high-frequency linear transducer is placed in a transverse orientation over the eye. The ONSD appears as a hypoechoic area posterior to the globe. The width should be measured 3 mm back from the globe. Measurement of ONSD can be seen in Figure 51.2.

When optic disc edema has been identified, or workup for papilledema/elevated ICP is required, neuroimaging is critical. Computed tomography (CT) is often the initial study because of its accessibility. However, magnetic resonance imaging (MRI) of the brain is the most sensitive study for intracranial pathology causing elevated ICP. Magnetic resonance venography (MRV) can also be performed simultaneously to evaluate for venous thrombosis. MRI may also demonstrate findings that can independently raise concern for increased ICP and papilledema (Table 51.2). These soft signs are not always present, and, therefore, their absence does not reliably exclude the presence of papilledema, and these findings may be present in individuals who do not ultimately have papilledema or increased ICP. Direct visualization of the optic disc is the only reliable way to exclude optic disc edema.