Metoptic canal, duplication of the optic canal and Warwick’s foramen in human orbits

Purpose: The region of the optic strut can be traversed by some minor canals whose incidence and general characteristics have never been studied. As such canals could be the route for vessels that could interfere in the surgery of the orbital apex we undertook a detailed anatomical study on a vast collection of dry skulls. Basic procedures: The examination of 943 dry adult skulls and 360 foetal skulls was carried out to precise the anatomy of canals in the optic strut area, their development and relationships with the optic canal. Main findings: A canal traversing the optic strut was present in 8.54% of the orbits. Based on diameter, position within the optic strut, and thickness of the bony plate separating it from the optic canal or from the superior orbital fissure, the canals piercing the optic strut were classified in four types which include the well-known duplication of the optic canal, different aspects of the metoptic canal and a type of canal that to our knowledge has never been reported. Warwick’s foramen was found in 0.74% of orbits. Principal conclusions: The area of the optic strut is the frequent site of canals joining the orbit with the middle cranial fossa. Some of them can host the ophthalmic artery, others could be run by minor vessels which, however, could be the source of annoying bleedings in surgical procedures.