any structural anomaly of the central retinal artery that branches off the ophthalmic artery, running inferior to the optic nerve within its dural sheath to the eyeball; this artery provides the majority of the retinal arterial supply except for the layer of cones and rods; it splits into multiple terminal branches within the ninth layer of retina, which then comprise a cobweb of retinal arterioles and capillaries that nourishes the inner retinal layers