[Radio-anatomical variants of the optic canal]

Two variants of the optic canal are described by the same patient. During the foetal development, the optic canal and the orbital fissure are first separated by an anterior strut, then by a posterior strut, who secondary fuse into a single optic strut. The keyhole anomaly of the optic canal results from the absence of the posterior optic strut. The duplicate cranial opening of the optic canal results from the absence of fusion of the anterior and posterior struts.