Indocyanine green angiography in birdshot chorioretinopathy

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Objective Birdshot chorioretinopathy (BC) is an ocular inflammatory disease involving both the retina and the choroid. The study goal was to evaluate indocyanine green angiographic features in BC to assess choroidal involvement. Design Retrospective, observational case series. Participants Fifty-two patients with BC documented with at least 1 concomitant fluorescein and indocyanine green angiogram. Intervention Indocyanine green angiography (ICGA) was performed according to a standard protocol used for inflammatory disorders. Main outcome measure Indocyanine green angiographic signs were correlated with fundus photographs, fluorescein angiography, degree of inflammatory activity, and stage of disease. Results In active disease, three main features were observed. The principal finding, found in 100% of patients, was the presence of hypofluorescent dark dots during the intermediate phase of angiography; their evolutionary pattern was twofold, becoming either isofluorescent or remaining hypofluorescent at the late phase of angiography. The other two signs were fuzzy, indistinct choroidal vessels and late-diffuse choroidal hyperfluorescence. In chronic longlasting disease, the characteristic finding was the presence of hypofluorescent dark dots that persisted in the late phase of disease and is theorized to correspond either to chorioretinal atrophy (irregular geographic pattern) or to persistent choroidal granulomas (round oval form). Conclusions Consistent ICGA findings in 52 patients allowed the authors to establish a fairly precise ICGA semiology for BC. This procedure enabled the authors to assess choroidal involvement, and, in selected cases, it also was found to be of diagnostic help and useful to monitor therapeutic intervention.