Predictability of Optic Foramen Location From a Ray Through the Ethmoidal Foramina

To determine how accurately a ray through the anterior and posterior ethmoidal foramina predicts the location of the optic foramen.

Dried, well-preserved, complete human skulls without bony defects belonging to the Hamann-Todd osteological collection of the Cleveland Museum of Natural History were examined. Photography was performed and a ray was drawn on orbit photographs extending through the center of the anterior and posterior ethmoidal foramina toward the optic canal. The location of the ray at the anterior aspect of the optic canal was recorded.

Sixty-six total orbits were examined from 36 skulls with 6 skulls with only unilateral data. Thirty-eight orbits were of African descent and 28 were of European descent with an average age 45.25 years (range = 19-89 years). The anterior-posterior ethmoidal foramen ray extended superior (12/66), through (53/66), and inferior (1/66) to the optic canal. Of those rays passing through the optic canal, 32/53 (60%) passed through the upper one-third, 19/53 (36%) passed through the middle one-third, and 2/53 (4%) passed through the lower one-third of the optic canal.

The anterior-posterior ethmoidal foramen ray highly predicts the superior aspect of the optic canal. This information can guide medial orbital wall surgery.