The Effects of Simultaneous Occlusion of the Posterior Ciliary Artery and Vortex Veins: A Histopathologic Study

Objective: In previous research, experimental occlusion of the posterior ciliary arteries resulted in an infarction of the retinal pigment epithelium and outer retina. A simultaneous occlusion of one or two vortex veins (VVs) appeared to have an ameliorative effect on the retinal infarct based on previous clinical and angiographic observations. The objectives of this report were to evaluate the histopathologic changes of the ischemic retina and to examine the disruption and healing of the blood-retinal barrier under various combinations of ciliary artery and VV occlusions. Methods: Experimental posterior ciliary artery (PCA) occlusion with (n=3) or without (n=3) simultaneous VV occlusion was carried out in six rhesus monkey eyes. The eyes were enucleated over a course of 3 months. The histopathologic changes of the ischemic retina were examined by light and electron microscopy. In addition, the horseradish peroxidase tracer technique was used to study the blood-retinal barrier. Results: Ischemic changes following the occlusion of the PCA consisted of coagulation necrosis of the retinal pigment epithelium and of the outer retinal layers and were less pronounced in eyes with simultaneous VV occlusion. At 6 hours after the insult, the blood-retinal barrier was broken and horseradish peroxidase leaked into the subretinal space (PCA occlusion with one VV occlusion). Three months later, the blood-retinal barrier had re-formed, even in the eyes with severe ischemic injury. Conclusions: The histopathologic changes suggest that the ameliorative effect of simultaneous VV occlusion on the effects of PCA occlusion might be due to reduced perfusion in the choroidal circulation.