Osmotically induced retinal detachment in the rabbit and primate. Electron miscoscopy of the pigment epithelium.

Previous work has shown that the injection of a hyperosmotic solution into the rabbit vitreous will cause rapid detachment of the retina. The present experiments show that osmotic detachment also occurs in the monkey eye. No anatomic changes were found to account for the early separation of the retina, but within a few minutes of detachment in the rabbit or several hours in the monkey, the retinal pigment epithelium microvilli lose their normal organization. This may be a nonspecific response to separation from the outer segments. After longer periods of osmotic detachment in the rabbit, the RPE cells became edematous and the microvilli shrank and disappeared. Although some cells ruptured at the apical membrane and large cysts were often observed above the cell junctions, the intercellular tight junctions always appeared intact. Osmolarity should be accounted for in the evaluation of intravitreal injections for man, and care should be used to avoid injection of concentrated solutes near the retina.