Choroidal fluorescein angiography in rabbit

Abstract

The extreme permeability of the choriocapillaris to sodium fluorescein makes angiography with this tracer unsuitable to show the choroidal vascular bed. In order to prevent this profuse leakage, the choroidal circulation is visualized with fundus angiography after injection of fluorescein isothiocyanate (FITC) labelled dextrans of different molecular weight: 20 000, 40 000, 70 000, and 150 000. It is shown that the two first dextrans leak out of the choriocapillaris rather rapidly, whereas the last two dextrans remain intravascularly long enough to enable good demonstration of choroidal vessels. The practical application of these findings is discussed, and it is concluded that the dextran with molecular weight 70 000 should be preferred for use in humans.