"Double-layer sign" on spectral domain optical coherence tomography in pachychoroid spectrum disease

Abstract

Purpose: The "double-layer sign (DLS)" describes the shallow and irregular elevation of the retinal pigment epithelium from the underlying intact Bruch's membrane visualized on the spectral domain optical coherence tomography. In this study, we evaluated the frequency, characteristics of the space within the double layer and other features in the pachychoroid spectrum to aid the clinical diagnosis of these variants.

Methods: This retrospective study evaluated the features of the DLS on multimodal imaging in consecutive patients with a clinical diagnosis of one of the four variants of pachychoroid: pachychoroid pigment epitheliopathy (PPE), pachychoroid neovasculopathy (PCN), chronic central serous chorioretinopathy (CCSCR), and polypoidal choroidal vasculopathy (PCV). The features of the DLS were graded by two masked graders.

Results: Overall, 102 eyes of 79 consecutive patients with pachychoroid spectrum were identified for grading. Sixteen eyes with PPE did not show any evidence of DLS. The DLS was identified in 15/16 (93.75%) eyes with PCN, 11/35 (31.43%) with CCSCR, and 32/35 (91.43%) with PCV (P < 0.001). The space within the DLS showed moderate hyperreflectivity in all eyes with PCV and PCN, while the space in the DLS in CCSCR showed uniform hyporeflectivity in 10/11 (%) eyes.

Conclusion: The DLS sign was most frequent in polypoidal vasculopathy and PCN. A hyporeflective gap within the DLS favored the diagnosis of CCSCR.

Keywords: Branching vascular network; chronic central serous chorioretinopathy; double-layer sign; optical coherence tomography; polypoidal choroidal vasculopathy.

Figure 1

Optical coherence tomography enhanced depth imaging (horizontal scan) through the fovea demonstrating subfoveal choroidal thickness measurement from outer portion of hyperreflective line corresponding to the retinal pigment epithelium to the inner portion of hyperreflective zone corresponding to the choroidoscleral junction (yellow vertical line)

Figure 2

Spectral domain optical coherence tomography (horizontal scan) showing the “Double-Layer Sign.” The inner layer is the hyperreflective irregularly elevated retinal pigment epithelium (dashed arrow), and the outer layer is the inner layer of the Bruch's membrane (solid arrow)

Figure 3

Spectral domain optical coherence tomography (horizontal scan) showing measurements of dimensions of double layer sign. Height of double-layer sign was defined as the greatest vertical distance measured from Bruch's membrane to the inner layer of retinal pigment epithelium (vertical yellow line, 105 μ), and the width was the widest horizontal dimension of the double-layer sign (horizontal yellow line, 3370 μ)

Figure 4

Spectral domain optical coherence tomography images representing the “Double Layer Sign” in both the disease entities. (a) In polypoidal choroidal vasculopathy eyes, the double-layer sign had a characteristic moderate hyperreflectivity in the space between the undulated retinal pigment epithelium (green arrow) and Bruch's membrane (yellow arrow). (b) In contrast, double-layer sign seen in chronic central serous chorioretinopathy showed uniform hyporeflectivity between the retinal pigment epithelium (green arrow) and Bruch's membrane (yellow arrow)

Figure 5

Spectral domain optical coherence tomography image of a hyper reflective double layer sign (bold white arrow) flanked on either side by a thumb-like pigment epithelium detachment (dashed white arrows)

Figure 6

Multimodal imaging showing various features associated with the Double Layer Sign in polypoidal choroidal vasculopathy. (a) Indocyanine green angiography image demonstrating nodular hyperfluorescence suggestive of polyp (bold white arrow) along with abnormal vascular network with feeder vessel suggestive of Branched Vascular Network dashed arrow). Dilated choroidal vessels in close proximity to the vascular network (dotted white arrow) are also seen. (b) Late phase indocyanine green angiography image showing area of late geographic hyperfluorescence (bold black arrows) at the site of Branched Vascular Network. (c) Indocyanine green angiography image with simultaneous spectral domain optical coherence tomography scan through the polyp and Branched Vascular Network confirming pigment epithelial detachment at the site of polyp (white star) with a hyperreflective double-layer sign in continuity with it (dashed and bold long white arrows). Underlying the double-layer sign, multiple large hyporeflective lumina are seen in the choroid (dotted small white arrows) suggestive of pachyvessels which corresponding to the site of dilated vessels on indocyanine green angiography. (d and e) Early and late fluorescein angiography images showing leakage at the site of double-layer sign (bold white arrows)

Figure 7

Multimodal image showing various features associated with the Double Layer Sign in chronic central serous chorioretinopathy. (a) Indocyanine green angiography image demonstrating the dilated choroidal vessels at the macula (bold white arrows). (b) Mid phase indocyanine green angiography image showing mid phase hyperfluorescence at the site of double-layer sign (bold black arrows). (c) Spectral domain optical coherence tomography scan at the level of Branched Vascular Network in indocyanine green angiography showing hyporeflective double-layer sign corresponding to Branched Vascular Network (dashed and bold long white arrows). Presence of pachyvessels noted beneath the double-layer sign depicted by hyporeflective large lumina in the choroid (dotted small white arrows). (d and e) Early and late fluorescein angiography images showing leakage at the site of double-layer sign (bold white arrows)

Figure 8

Multimodal image showing various features associated with the Double Layer Sign in Pachychoroid neovasculopathy. (a) Indocyanine green angiography image demonstrating abnormal vascular network suggestive of Branched Vascular Network (dashed arrow) that leaks minimally in late phases of indocyanine green angiography (dotted white arrow, b) (c) indocyanine green angiography image with simultaneous spectral domain optical coherence tomography scan illustrating a hyperreflective double-layer sign (dashed white arrow). Underlying the double-layer sign, multiple large hyporeflective lumina are seen in the choroid (bold white arrows) suggestive of pachyvessels that are corresponding to the site of dilated vessels on indocyanine green angiography (bold white arrows). (a and e) Early and late fluorescein angiography images showing leakage at the site of double-layer sign (dotted white arrows)