[Choroidal blood flow in chronic stage of selective retinal damage after monoiodoacetic acid injection]

The present study was carried out to determine changes in the choroidal circulation after a long period following selective damage of the outer layer of the retina. Monoiodoacetic acid was given to rabbits via an ear vein at a dosage of 40 mg/kg. The choroidal blood flow (CBF) at three and six months after selective damage was measured by the hydrogen clearance method and histological change was studied by light and electron microscopy. CBF decreased by 19% at three months and 22% at six months, the values in the experimental groups being significantly less than those of controls. Histological findings at six months were essentially the same as those at three months. The outer layer of the retina was totally replaced by glial cells. Some retinal pigment epithelial cells (RPE) had disappeared. The remaining RPE indicated proliferative or atrophic changes. At the site where RPE had disappeared, fibrous changes were evident in the inner layer of the choroid and choriocapillaris were lost. CBF at this site decreased significantly compared to that of the acute stage following monoiodoacetic acid administration. The outer layer of the retina, particularly RPE, may be reciprocally related to CBF and modulate choroidal angio-architecture.