Experimental retinal detachment. VIII. Retinochoroidal horseradish peroxidase diffusion across the blood-retinal barrier.

Unilateral rhegmatogenous retinal detachments in 13 cynomolgus monkeys were studied with horseradish peroxidase (HRP). When injected subretinally in six eyes, HRP did not diffuse anteriorly into the sensory retina and penetrated posteriorly through the zonulae occludentes of the retinal pigment epithelium (RPE) in only two eyes. In seven eyes, tracer was detected after intravitreal HRP injection throughout the sensory retina, the basal lamina of retinal blood vessels, and the subretinal space, but did not penetrate through the RPE. In 13 control eyes (with vitrectomy), intravitreal HRP penetrated the sensory retina and the basal lamina surrounding inner retinal blood vessels. These results confirm that the zonulae occludentes of the RPE and retinal blood vessels remain intact in most eyes after rhegmatogenous retinal detachment. Furthermore, the HRP staining patterns suggest a posteriorly directed movement of fluid across the RPE and possible fluid absorption by retinal blood vessels.