Changes of Blood-Retinal Barrier Induced by Destruction of the Retinal Pigment Epithelium

ABSTRACT

The author studied the functional derangement of blood-retinal barrier induced by destruction of the pigment epithelial cells of the retina. Sodium iodate, which was well known to exert a selectively destructive action to the retinal pigment epithelial cells, was injected to the rabbits intravenously(60mg/kg of body weight). Eyes were enucleated 2 days and 4 days after sodium iodate injection and examined by electron microscope. Some of the tissue were fixed in colloid lanthanum, to investigate the changes of the permeability of plasma membrane in accordance with cellular damages induced by sodium iodate. The permeability of the blood-retinal barrier was also studied after intravenous(200mg/kg) or intraocular(4 microgram/20ml of saline) injection of horseradish peroxidase(HRP). The results obtained were summarized as the following Sodium iodate induced patchy areas of loss of pigment epithelial cells after 2 days, which were more widespread and severe after 4 days with regenerative activities. Loss of outer segment and mitochondrial swelling of the inner segment of visual cells were also noted after 4 days. Colloidal lanthanum penetrated into the mitochondria of pigment epithelial cells at 2 days after sodium iodate injection, which was extended to the mitochondria of inner segment of visual cells after 4 days. Intraocularly injected HRP appeared from the internal limiting membrane to Bruch's membrane after 2 days. Intravenously injected HRP appeared from the Bruch's membrane to ganglion cell layer after 2 days, which were extended to the vitreal cavity. The results suggested that the damage of the pigment epithelial cells induced by sodium iodate destroy blood-retinal barrier. HRP exudation is more extensive in direction of retina to choroid than choroid to retina.