Experimental carotid occlusion: funduscopic and fluorescein angiographic findings

A characteristic fundus picture was consistently produced following acute bilateral common carotid artery ligation in mature rats, reminiscent of human carotid occlusive disease. Two days after ligation it consisted of dilatation and tortuosity of retinal veins, blurring and swelling of the optic disc, retinal whitening primarily along the venous distribution, and straightening of retinal arteries. Fluorescein angiography showed hyperfluorescence of the disc, delay in the rate of retinal arterial and venous filling, venous dilatation, disc oedema, disruption of the retinal capillary bed pattern, and late peripapillary staining/leakage. This pattern was not seen in rats which underwent acute unilateral ligation, although some mild changes were seen on fluorescein angiography. The vascular alterations seemed to regress spontaneously within one week. A peripapillary 'halo' and a granular-appearing nerve fibre layer developed later, exclusively in bilaterally ligated animals.