Hematic and fluid barriers of the retina and vitreous body

A method employing non‐toxic doses of diaminoacridines combined with ultrafreezing and drying techniques, fluorescent microscopy, and fluorometry has been used in this study of hematic and fluid barriers in the vitreal chamber and surrounding tissues. These studies have demonstrated: that diaminoacridine concentrations of 3.38 × 10−6 M in the circulating blood failed to penetrate into the retina, vitreous body, and optic nerve head; that there are hematic barriers preventing the penetration of diaminoacridines into these tissues and fluids; that the barriers are located in the pigment epithelium, inner layer of ciliary epithelium, iridial retina, and vascular endothelium of retinal and optic nerve vessels; and that the precise anatomical sites of these barriers are given by (a) the part of the cell membrane of ciliary epithelium and iridial retina facing the posterior eye chamber, (b) the part of the cell membrane of pigment epithelium facing the retina, and (c) the part of the endothelial cell membrane of retinal and optic nerve head vessels facing the vascular lumen. Injections in the vitreal or aqueous chambers to produce 3.38 × 10−6 M diaminoacridine concentrations inside either chamber have demonstrated that the hematic barriers which prevent the penetration of diaminoacridines from the blood into the retina and vitreous permit their passage in the opposite direction. The diaminoacridine solutions follow special patterns in their elimination from the vitreous of different species according to the type of retinal vascularization.