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

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.

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.

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.

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