Optic nerve sheath fenestration is a surgical procedure designed to reduce pressure or swelling in the space surrounding the optic nerve. The optic nerves at the back of each eye carry vision signals to the brain. Vision is at risk if these nerves become significantly swollen. The procedure of optic nerve sheath fenestration involves making a small hole in the protective covering tissue that surrounds the optic nerve, known as the optic nerve sheath. This allows excess fluid to drain from the space surrounding the nerve and reduces swelling and pressure on the nerve.
Jameson, J. Larry, et al. Harrison's Principles of Internal Medicine, 20th Ed. New York: McGraw-Hill Education, 2018.