Differentiating Optic Disc Edema From Optic Nerve Head Drusen on Optical Coherence Tomography

Abstract

To assess optical coherence tomography in differentiating optic disc edema (ODE) due to papilledema and other optic neuropathies from optic nerve head drusen (ONHD). Methods: Optical coherence tomographic images from 60 subjects (20 with ODE, 20 with ONHD, and 20 control subjects) were assessed qualitatively and quantitatively. Qualitative criteria for ODE included an elevated optic nerve head with smooth internal contour and subretinal hyporeflective space (SHYPS) with recumbent "lazy V" pattern. Optic nerve head drusen displayed a "lumpybumpy" internal optic nerve contour and a rapid decline in SHYPS thickness. Quantitative comparisons included retinal nerve fiber layer and SHYPS thickness. Results: Optical coherence tomography differentiated ODE from ONHD qualitatively (sensitivity, 63%; speci-ficity, 63%) and quantitatively (sensitivity, 80%; specificity, 90%). Respective differences in mean retinal nerve fiber layer thickness between ODE and ONHD were significant (P Ͻ .002) superiorly (206.8 vs 121.7 µm), nasally (176.3 vs 78.6 µm), inferiorly (247.2 vs 153.8 µm), and temporally (180.0 vs 85.5 µm). Respective differences in mean SHYPS thickness between ODE and ONHD were significant (PϽ .001) at radii of 0.75 mm (512.1 vs 274.4 µm), 1.5 mm (291.4 vs 103.0 µm), and 2.0 mm (145.5 vs 60.7 µm). Conclusion: Optical coherence tomography can differentiate ODE from ONHD, particularly when the nasal retinal nerve fiber layer and SHYPS thickness at the 2.0-mm radius are greater than 86 µm and 127 µm, respectively.

Increased Prevalence of Optic Disc Drusen after Papilloedema from Idiopathic Intracranial Hypertension: On the Possible Formation of Optic Disc Drusen

“…3 Eyes identified as having ODD on OCT had classic findings of drusen as shown in Figure 1. Supplementary findings included normal intracranial pressure on lumbar puncture and persistence of disc elevation on follow-up examinations.…”

“…[1][2][3][4] ODD are often identified on routine clinical examination, without a history of known optic nerve disorder. Postmortem and in vivo studies have documented histologically that drusen are composed of calcium and phosphorous crystals (Ca 3 (PO 4 ) 2 ).…”

Optical Coherence Tomography and Optic Nerve Edema

“…Various methodologies have been used to study buried ONHD, including fundus autofl uoresence, B-scan ultrasonography, computerized tomography, and fl uorescein angiography [ 60 ]. Currently, B-scan ultrasonography is commonly used in the clinical evaluation of ONHD.…”

“…Patients with optic disc edema, on the other hand, had an elevated optic nerve head with a smooth internal contour, a recumbent "lazy V" pattern of the subretinal hyporefl ective space with an increased thickness at the 2.0 mm radius, and an increased RNFL thickness with a nasal RNFL greater than 86 microns. They found a nasal RNFL thickness greater than 86 microns has 80 % specifi city and a subretinal hyporefl ective space thickness greater than 169 microns at 2.0 mm radius has 90 % specifi city in differentiating between optic disc edema and ONHD [ 60 ].…”

Pseudotumor Cerebri (Idiopathic Intracranial Hypertension) an Update

“…At present, clinical evaluation of the optic nerve head volume, better reflects the overall degree of optic nerve head edema rather than the thickness of the RNFL alone, since volume measurement incorporates the volume of both the total optic nerve height and the sub-retinal hypo reflective space. (Johnson et al, 2009). …”