Histologic localization of sodium fluorescein in human ocular tissues

We studied the distribution pattern of sodium fluorescein in human eyes microscopically. The ciliary body showed early and diffuse leakage, with staining of the basement membrane of the nonpigmented ciliary epithelium, indicating movement of fluorescein from the ciliary body into the aqueous humor. After five minutes the iris stroma stained with fluorescein, probably from the aqueous humor. The retinal vessels and retinal pigment epithelium were impermeable to fluorescein. Corresponding to the background fluorescence seen in fluorescein angiography, fluorescence was present in Bruch's membrane and in the stroma of the inner one third of the choroid. Drusen stained most intensely in areas of greatest PAS positivity. Early fluorescence of the optic disk was the result of intravascular perfusion of the dye. Minimal diffusion of fluorescein from the fenestrated choroidal vessels across the border tissue of Elschnig into the peripheral optic nerve bundles was observed. Late fluorescence of the optic disk was due mainly to fluorescein staining of the lamina scleralis and glial columns.