Haller's Circle

HALLER'S CIRCLE (circulus Halleri), a vascular scleral venetian ring located directly at the point where the optic nerve enters the sclera. It is formed by 2-3 branches of the short posterior ciliary arteries, which, anastomosing with each other, give rise to a ring surrounding the point of entry of the optic nerve. From this ring, branches extend 1) to the optic nerve, anastomosing there with branches of the central artery, 2) to the vascular network of chorioideae, and 3) to the nearest parts of the retina. Thus, a connection is established here between the ciliary and retinal systems of blood vessels. Sometimes, individual branches of Haller's ring, forming a bend, extend forward into the retina and, under the name of cilio-retinal vessels, proceed to the area of the macula, nourishing the corresponding area of the retina.