The "double-layer sign": in vivo imaging of polypoidal choroidal vasculopathy

Polypoidal choroidal vasculopathy (PCV), a disease of the choroidal vascular network, presents clinically with polyp-like reddish orange lesions, as well as retinal pigment epithelial (RPE) and/or neurosensory retinal detachments. Optical coherence tomography (OCT) is a useful diagnostic tool that provides cross-sectional and volumetric imaging of posterior segment microstructure. Typical OCT findings in PCV may reveal a classic hyperreflectivity in the choroidal layers known as the "double-layer" sign. This sign is indicative of an abnormal choroidal vascular network. Indocyanine green angiography is also useful for the diagnosis of PCV and clearly identifies the polyp-like lesions arising from the choroidal vasculature.

A 53-year-old African American woman presented with complaints of gradually decreasing vision in the left eye (OS). Clinical examination revealed moderately reduced acuity OS with a small central scotoma found on Amsler grid testing. Dilated fundus examination revealed a hemorrhagic RPE detachment with suspicion of a choroidal neovascular membrane in the foveal region of the OS. Exudative leakage appeared circumferentially around the macula OS. Optical coherence tomography of the OS also revealed two highly reflective layers: one at the level of the RPE and another beneath the RPE ("double-layer" sign). The patient was referred to a retina subspecialist for angiography and treatment consideration.

It is important to distinguish PCV from other variants of choroidal neovascularization. The polyp-like lesions found in the PCV are a unique and classic characteristic. Proper diagnostic workup includes stereoscopic posterior fundus evaluation and imaging studies, including OCT and indocyanine green angiography.