The distance between the posterior ethmoidal foramen and optic canal is more than double the distance quoted in the surgical literature. This is due to a high incidence of ethmoidal foramina variation. Surgeons operating on the medial orbital wall of a Caucasian population must be aware of these variations as they are a source of haemorrhage and act as landmarks of proximity to the optic canal.

The presence of the cranio-orbital foramen and other accessory foramina represents a source of hemorrhage that surgeons should be aware of when operating along the lateral orbital wall.