A cadaveric study of ethmoidal foramina variation and its surgical significance in Caucasians

Aims To describe the morphometric and geometric relationships of the medial orbital wall ethmoidal foramina and the orbital apex in a Caucasian population. Methods 47 orbits from 24 formalin-fixed cadavers were exenterated. Morphometric measurements were taken between anatomical landmarks located on the medial orbital wall and geometric values were calculated. Results The average distances from the anterior lacrimal crest to the anterior ethmoidal foramen, posterior ethmoidal foramen and optic canal were 25.61 mm (±2.25), 36.09 mm (±3.86) and 43.77 mm (±2.52), respectively. The average distances from the anterior ethmoidal foramen to the first posterior ethmoidal foramen, last posterior ethmoidal foramen and optic canal were 13.88 mm (±3.51), 16.60 mm (±2.19) and 21.65 mm (±2.59), respectively. The average distances from the first and last posterior ethmoidal foramen to the optic canal were 11.63 mm (±3.79) and 7.25 mm (±2.59), respectively. Conclusion 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.