[Persistence of the perioptic ring of the ophthalmic artery. Anatomical and embryological observations].

At the foetal age, there is an arterial ring around the optic nerve inside the orbit. This ring, partially supplied by the ophthalmic artery, is transitory. A persistence at the adult age is absolutely exceptional. The case described in this paper is the second to be published. It has been found during a microdissection of the arteries of the orbit muscles. The authors discuss the variations of the origin and the course of the ophthalmic artery, according to the three embryologic origins of the orbital arterial vascularization: dorsal and ventral ophthalmic arteries, hyoïd artery. This multiple origin explains the formation of the ring and its persistence.