The present investigation was undertaken to demonstrate the distribution of fluorescein sodium in the choroid and retina after the dye was given intravenously. It has been thought that it is difficult to ascertain the exact location of the dye in histologic sections on account of the diffusion properties of apueous fluorescein. I could clearly demonstrate the distribution of the dye in the choroid and retina.
Under Nembutal anesthesia, rhesus monkeyes and albino rabittes weighing 2 kg were given intravenously 0.5m1 of 5 % fluorescein sodium. Also pigmented rabbittes after the photocoagulation were examined. The bulbus was removed 8,9,10,30 seconds and 2,4,10,20 and 60 minutes after the dye injection.10μ thick frozen-dried sections were made and examined with fluorescence microscope.
The results obtained are as follows: The blood vessels, large or small, of retina and optic disc are impermeable to fluorescein. Although fluorescein diffuses rapidly throughout the choroid, none passes the pigment epithelium to enter the retina. In contrast, at the posterior scleral foramen some fluorescein enters the optic disc by diffusion from neighbouring choroid. At the optic disc retina is protected from fluorescein by the intermediary tissue of Kuhnt. In the optic nerve fluorescein diffuses from the vessels to connective septa, but never enters the nerve fivers. After the photocoagulation the dye diffuses to retina.
