The effects of simultaneous occlusion of the posterior ciliary artery and vortex veins. A histopathologic study
K. U. Loeffler, S. S. Hayreh and M. O. Tso
Georgiana Dvorak Theobald Ophthalmic Pathology Laboratory, University of Illinois at Chicago.
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.
