Vascular pathways of the anterior segment of the canine eye.

The vasculature of the anterior segment of the canine eye was studied by preparing intravascular casts with a methyl methacrylate resin. Specimens were examined and results were recorded with the aid of stereoscopic dissecting and scanning electron microscopes. The arterial supply was via anterior ciliary and long posterior ciliary arteries. An arterial circle derived from dorsal and ventral anterior ciliary arteries was identified in the anterior sclera. The long posterior ciliary artery contributed branches to the choroid, anterior sclera, and anterior border of the ciliary processes. Radial iris arterioles arose from the major arterial circle of the iris and ended blindly at the pupillary margin. Radial ciliary arteries arose from the major arterial circle of the iris and ran posteriorly and supplied the ciliary processes and muscle and fused with the choroidal vasculature. Each ciliary process was supplied by an afferent arteriole from the radial ciliary artery. Sphincters could be seen at branch points within the vascular net of the ciliary processes.