Dark Signals in the Choroidal Vasculature on Optical Coherence Tomography Angiography: An Artefact or Not?

Figure 6

OCTA in a case of outer retinal atrophy. (a) Multicolour image showing a round penetrated hyperreflective region in the macula indicating atrophy of the RPE. (b) SD-OCT showing enhanced choroid in the atrophic RPE area, as compared with the neighbouring normal region (inserted image indicates the direction of OCT scanning). (c) Corresponding cross-sectional OCTA confirms that the remaining fine vessels become obvious with a clear outline after neighbouring regional atrophy, in contrast with the relatively dark background (red dash-dotted box) when compared with normal tissues (yellow dash-dotted box). (d) Infrared image showing the boundary between atrophic and normal areas. (e) En face OCTA shows a hypointense halo beneath the normal RPE and continuing hyperreflective vascular signals due to the masked effect (red arrows in (d) and (e)). OCTA: optical coherence tomography angiography; RPE: Retinal pigment epithelium; SD-OCT: spectral-domain optical coherence tomography.

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