Water movement from the vitreous to the choroid would tend to maintain retinal apposition, if the retina were less permeable than the retinal pigment epithelium (RPE). We used a rabbit model, to test the relative permeability of retina and RPE to tritiated water. The retina was found less permeable than the RPE. This result suggests the presence of a hydrostatic pressure gradient across the retina which could enhance apposition of retina to the RPE.
Key words retinal apposition - water movement - rabbit - composite membranes - barriers - vitreous - retina - retinal pigment epithelium