The orbits are bony cavities that contain the globes, extraocular muscles, nerves, fat, and blood vessels. Each bony orbit is pear shaped, tapering posteriorly to the apex and the optic canal. The medial orbital walls are approximately parallel and are separated by 25 mm in the average adult. The widest dimension of the orbit is approximately 1 cm behind the anterior orbital rim. Average measurements of the adult orbit are shown in Table 1-1. The intraorbital segment of the optic nerve has an S-shaped curve, allowing the eye to rotate and move forward with some freedom, without placing excessive tension on the posterior globe insertion (globe tenting).
Table 1-1 Average Dimensions of the Adult Orbit
Excerpted from BCSC 2020-2021 series: Section 10 - Glaucoma. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.