The Tenon Capsule
The Tenon capsule (fascia bulbi) is the principal orbital fascia and forms the envelope within which the eyeball moves (Fig 3-6). The Tenon capsule fuses posteriorly with the optic nerve sheath and anteriorly with the intermuscular septum at a position 3 mm from the limbus. The posterior portion of the Tenon capsule is thin and flexible, enabling free movement of the optic nerve, ciliary nerves, and ciliary vessels as the globe rotates, while separating the orbital fat inside the muscle cone from the sclera. At and just posterior to the equator, the Tenon capsule is thick and tough, suspending the globe like a trampoline by means of connections to the periorbital tissues. The global layer of the 4 rectus muscles penetrates this thick fibroelastic tissue approximately 10 mm posterior to their insertions. The oblique muscles penetrate the Tenon capsule anterior to the equator. The Tenon capsule continues forward over these 6 EOMs and separates them from the orbital fat and structures lying outside the muscle cone.
A, Anterior and posterior orifices of the Tenon capsule shown after enucleation of the globe. B, The Tenon space shown by injection with India ink.
(Modified with permission from von Noorden GK, Campos EC. Binocular Vision and Ocular Motility: Theory and Management of Strabismus. 6th ed. St Louis: Mosby; 2002:45.)
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.