Which glial tissue separates the optic nerve fibers from the choroid?

• A. Border tissue of Jacoby
• B. Intermediary tissue of Kuhnt
• C. Intermediary tissue of Javal
• D. Border tissue of Elschnig

Answer: (A)

The key idea is the boundary where neural retina ends and the vascular choroid begins at the optic nerve head. The border tissue of Jacoby is a glial extension at this inner scleral border that forms a barrier between the optic nerve fiber layer and the underlying choroid. It is the specialized tissue that physically separates the unmyelinated nerve fibers from the choroidal tissue, helping define the edge of the neural retina as it enters the optic nerve.

Other border tissues around the disc mark different interfaces, such as the choroid-sclera margin, and the intermediary tissues of Kuhnt and Javal refer to other retinal glial layers that don’t serve this specific boundary between nerve fibers and choroid.