cell development establishment of blood-retinal barrier sl establishment of blood-retina barrier establishment of BRB biological_process GO:1990963 2016-06-07T21:17:55Z Establishment of the barrier between the blood and the retina. The blood-retinal barrier is located at two levels, forming an outer barrier in the retinal pigment epithelium and an inner barrier in the endothelial membrane of the retinal vessels. Both these membranes have tight junctions of the 'nonleaky' type.