Assessment and classification of choroidal vasculitis in posterior uveitis using indocyanine green angiography.

Background: By allowing one to detect fluorescence beyond the retinal pigment epithelium, indocyanine green angiography (ICGA) has made it possible to analyse the choroidal vessels. Our aim was to characterize choroidal vasculitis in posterior uveitis using ICGA.
Methods: Charts of active posterior uveitis patients with a specific diagnosis seen in the different centers participating in the study who had undergone dual fluorescein and ICG angiography were reviewed. The type of inflammatory involvement of the choroidal circulation at entry and the treatment response on follow-up angiograms were analysed.
Results: A total of 129 patients were analysed. Choroidal vasculitis could be subdivided into two main patterns: (1) primary inflammatory choriocapillaropathy and (2) stromal inflammatory vasculopathy. The first pattern consisted of hypofluorescent areas up to the late phase of angiography characteristic for choriocapillaris non-perfusion and included entities such as multiple evanescent white dot syndrome (MEWDS), acute posterior multifocal placoid pigment epitheliopathy (APMPPE), multifocal choroiditis (MC), ampiginous choroidopathy and serpiginous choroidopathy. The second pattern consisted of fuzzy indistinct appearance of vessels in the intermediate angiographic phase and diffuse choroidal hyperfluorescence in the late phase indicating inflammatory vasculopathy of larger choroidal vessels. This pattern was found in all cases of active Vogt-Koyanagi-Harada disease, ocular sarcoidosis and tuberculosis and birdshot chorioretinopathy. In Behçet's uveitis of recent onset, choriocapillaris perfusion delay and fuzzy choroidal vessels without diffuse late choroidal hyperfluorescence was found. In posterior scleritis, enlargement of vorticous veins was an additionnal ICGA sign. Stromal inflammatory vasculopathy always responded to anti-inflammatory therapy. A third group of patients with severe retinal or choroidal inflammation presented with associated secondary inflammatory choriocapillaropathy angiographically identical to the primary involvement.
Conclusions: ICGA allowed the hitherto impossible characterization of inflammatory involvement of the choroidal vessels, showing either predominant inflammation of the choriocapillaris or predominant inflammation of the stromal choroidal vessels with or without secondary choriocapillaritis. ICGA will be indispensable for the correct evaluation and follow-up of posterior inflammation with suspected choroidal involvement.