Unilateral persistence of the dorsal ophthalmic artery in man.

The left ophthalmic artery (OA) of a Caucasian male originated from the transverse portion of the cavernous part of the internal carotid artery (ICA), indicating the persistence of a dorsal OA. It entered the orbit through the most medial part of the superior orbital fissure, close to the medial aspect of the ophthalmic nerve. In the orbital cavity, the OA crossed above the optic nerve to reach the medial wall of the orbit. At the medial end of the upper eyelid it anastomosed with the angular artery and thereafter divided into the dorsal nasal and supratrochlear arteries. Whereas the right OA did not present any irregularities, some additional anatomical variations, above all a bilateral pterygospinosus muscle, were found in this individual. Since except the existence neither the course and branching pattern of a persistent dorsal OA nor its occurrence together with other varieties have been previously reported in man, phylogenetic and ontogenetic aspects of this aberrant vessel are discussed.