The choroidal circulation completely separated from the retinal circulation has not, to our knowledge, been previously demonstrated by fluorescein angiography. This has been accomplished in owl monkeys and rabbits by direct injection of fluorescein via a catheter introduced into a vortex vein by microsurgical technique. Morphologically distinct choroidal venous and arterial patterns were angiographically demonstrated in monkeys and rabbits. Some direct perfusion to the optic disc from the adjacent choroidal circulation was demonstrated in both species.
Tsai ENC, Smith JL. Experimental Vortex-Choroidal Angiograms. Arch Ophthalmol. 1975;93(3):198-206. doi:10.1001/archopht.1975.01010020206008