LAUSR

Clinical examination of the disc has been validated as a powerful tool to make the distinction between true and pseudo disc edema. Frisen grading of papilledema allowed this distinction to become easier, especially in higher grades of disc edema.[1] In the earlier grades of papilledema, a nasal margin of the disc is first involved followed by the superior and inferior margins. Progressively, the entire disc circumference is involved. The axonal swelling causes the blood vessels crossing the disc margin and the major vasculature over the disc to be variably obscured depending on the grade of the edema. B scan ultrasonography has been regularly employed, where in the hyperreflective echo of the disc drusen is easily recognized in cases with diagnostic confusion. However, Carter et al. in their study utilizing orbital ultrasonography found that 21% of pseudopapilledema eyes had dilated optic nerve sheaths (a feature of papilledema). They thus advised caution in the interpretation of ultrasonography results in patients with pseudopapilledema.[2] Optical coherence tomography (OCT) has also been studied to help distinguish between optic nerve head drusen (ONHD) and papilledema. ONHD is known to have a lumpy, bumpy appearance, whereas papilledema has a “lazy V contour” due to subretinal fluid.[3] Scott et al. went a step further in comparing clinical assessment of papilledema and OCT findings. They concluded that OCT was more helpful in lower grades of papilledema when the diagnosis was doubtful and unhelpful in higher grades because of segmentation errors.[4] The sensitivity and specificity of OCT in diagnosing papilledema is 80% and 70%, respectively.[5] Autofluorescence is another important tool that picks up a disc drusen by its characteristic hyperautofluorescence, although it may not help in buried drusen. There is no single test possessing high sensitivity and specificity to definitively distinguish between true and pseudo disc edema.