Abstract
Abstract: :
Purpose: To examine how removal of retinal pigment epithelium (RPE) affects choroidal circulation in rabbits Methods: The retina and choroid were examined by biomicroscopy, scanning laser ophthalmoscopy, fluorescein and indocyanine green angiography and histology at various times after the removal of the RPE by gentle aspiration following a local vitrectomy and bleb detachment. We compared small and large areas of RPE removal as well as only slight pressure without RPE removal. Results: Removal of the RPE layer causes leakage of vascular fluid into the subretinal space for at least a week after surgery as well as a loss of perfusion in the choroidal vessels and choriocapillaris at the debridement site. This reduction of local choroidal blood flow can occur within minutes after surgery and be either transient or permanent. The permanent changes are due to fibroblastic infiltration that compresses the choroidal vessels. Permanent changes tend to occur after removal of large areas of RPE. Removal of small areas or slight pressure on the retina causes a transient loss of local choroidal perfusion before any fibroblastic infiltration can occur. Conclusions: Removal of the RPE produces areas of non-perfusion in both large choroidal vessels as well as the choriocapillaris. There are at least two phases to this process. One is sudden and potentially reversible. The second occurs later and is permanent. Pressure alone or removal of small areas of RPE cause the former. The latter occurs after removal of large areas of RPE and is due to choroidal fibrosis. The former must be due to a rapid, local reduction in choroidal flow that is initiated by an insult to the RPE and/or choroid. The existence and change in these areas of non-perfusion are best observed by serial angiography.
Keywords: choroid • pathology: experimental • retinal pigment epithelium