• Fluorescein iris angiography was performed in 42 normal blue or green human eyes to investigate the normal angiographic pattern and in vivo circulation of the iris. Brown irides were unsuitable for the angiography because the brown pigment masked fluorescence. The pattern in the iris was much more complex than in the retina when seen on fluorescein angiography, with interindividual variations in its filling, and these physiological variations may erroneously be considered pathological. Radial arteries of the iris filled rather sluggishly and the circulation in the pupillary and peripupillary region was often much slower than in the peripheral part of the iris. Various segments of the iris usually filled in an irregular order. There was no distinct venous phase, but it merged with the arteriovenous phase. The pupillary region of the iris between the collarette (which contained a fragmented and incomplete minor circle of vessels) and the pupillary margin contained a dense plexus of capillaries. The normal vessels usually showed no fluorescein leakage.
Hayreh SS, Scott WE. Fluorescein Iris AngiographyI. Normal Pattern. Arch Ophthalmol. 1978;96(8):1383-1389. doi:10.1001/archopht.1978.03910060137009