The resorption of subretinal fluid after diffuse damage to the retinal pigment epithelium

We studied the role of the retinal pigment epithelium (RPE) in the resorption of different subretinal fluids from under small experimental retinal detachments (blebs) in the rabbit. Damaging the RPE with sodium iodate caused the resorption time, for blebs made with an ionic solution (Hanks'), to decrease from 2-6 hours to only about 30 minutes. Blebs made with sucrose also absorbed much more quickly after iodate. However, blebs made with autologous serum resorbed no faster after iodate. We conclude that iodate destroys the membrane barrier properties of the RPE, allowing subretinal fluid to cross freely according to oncotic pressure. We postulate that in the normal eye, where osmotic fluid movement is low because of the high resistance barrier, the RPE must transport fluid actively to keep the subretinal space dehydrated.