Prolonged retinal arterio-venous circulation time by fluorescein but not by indocyanine green angiography in birdshot chorioretinopathy

Purpose: To compare retinal arterio-venous circulation time by fluorescein (FA) and indocyanine green angiography (ICGA) in birdshot chorioretinopathy. Methods: We analysed prolonged retinal arterio-venous fluorescein transit time, a known feature in birdshot chorioretinopathy and correlated it with ICGA findings in four consecutive patients. Results: Mean retinal arterio-venous fluorescein circulation time was 31.1+/-5.2 seconds, a transit time significantly longer than in a group of ten patients with sarcoidosis (9.45+/-3.36 sec., p<0.0001) and in a group of three cases with Vogt-Koyanagi-Harada disease (7.0+/-1, 1 sec., p<0.0001). Conclusion: Prolonged fluorescein arterio-venous transit time seems to be a characteristic feature of birdshot chorioretinopathy that does however not reflect the actual intravascular hemodynamic situation but diffuse blood-retinal barrier damage allowing exudation, slow gradual tissue impregnation and delayed venous reabsorption of small molecules like fluorescein.