Morphologic and fluorangiographic study of the feline retina

Abstract

The microvasculature of the feline retina was studied using the techniques of histology, vascular corrosion casts and fluorescein angiography. The feline retina is holangiotic. It is irrigated by several large retinal arterioles and venules which are situated in the nerve fibre layer and ganglion cell layer of the retina and usually do not bulge into the vitreous body. The smaller arterioles, capillaries and venules are organized into an inner plexus, located in the ganglion cell layer, and an outer plexus, located between the inner nuclear layer and the outer plexiform layer. At the level of the area centralis retinae there are no large blood vessels but only capillaries, small arterioles and venules. On fluorescein angiography, the fluorescence in the retinal arterioles occurs nearly simultaneously with that in the choriocapillaris. The retinal arterio-venous phase is characterized by a complex filling of the smaller arterioles and capillaries which show the most pronounced contrast at the level of the non-tapetal area. In the early-venous phase, fluorescence starts in the smaller retinal venules which drain the area centralis region, followed by filling of the largest venules, whereby lamination of fluorescence can be observed. During the late-venous phase, these venules are homogeneously and completely filled