Tenon's capsule (/təˈnoʊn/), also known as the Tenon capsule, fascial sheath of the eyeball (Latin: vagina bulbi) or the fascia bulbi, is a thin membrane which envelops the eyeball from the optic nerve to the corneal limbus, separating it from the orbital fat and forming a socket in which it moves.

This lymph space is continuous with the subdural and subarachnoid cavities and is traversed by delicate bands of connective tissue which extend between the capsule and the sclera.

Charles Barrett Lockwood described a thickening of the lower part of Tenon's capsule, which he named the suspensory ligament of the eye.

It is slung like a hammock below the eyeball, being expanded in the center, and narrow at its extremities which are attached to the zygomatic and lacrimal bones respectively.

A blunt, curved cannula is passed through the incision into the periscleral lymph space and a volume of local anaesthetic solution is instilled.