The optic nerve and surrounding arachnoid sheath are tethered to the periosteum of the bony canal in the intracanalicular region. In blunt trauma, particularly over the eyebrow, the force of injury can be transmitted to the intracanalicular region, causing shearing and interruption of the blood supply to the nerve in this area. Such nerve damage is called indirect traumatic optic neuropathy. In addition, optic nerve edema in this area can lead to a compartment syndrome, further compromising the function of the optic nerve within the confined space of the optic canal.
Excerpted from BCSC 2020-2021 series: Section 2 - Fundamentals and Principles of Ophthalmology. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.