Conjunctival sac - Eye - Anatomical cross sections - e-Anatomy
View the module

Conjunctival sac

Saccus conjunctivalis

Definition

Antoine Micheau & Muhammad A. Javaid

The conjunctival sac is the potential space formed between the palpebral conjunctiva lining the eyelids and the bulbar conjunctiva covering the anterior surface of the sclera. When the eyelids are closed, it becomes a closed sac; when the eyes are open, it communicates with the exterior through the palpebral fissure.

The conjunctival sac is bounded by:

The conjunctival fornices are loose and flexible folds that permit free movement of the eyeball and eyelids.

Histology

Histologically, the conjunctival sac is lined by nonkeratinized stratified columnar epithelium with numerous goblet cells, especially in the fornices. Beneath the epithelium lies the substantia propria, a vascular connective tissue layer containing lymphoid tissue and immune cells.

Functions

Functionally, the conjunctival sac:

  • Allows smooth movement of the eyelids over the eyeball

  • Distributes tears across the ocular surface

  • Contributes to lubrication through mucin secretion by goblet cells

  • Participates in immune defence of the eye

Is this definition incorrect or incomplete?

References

  • Shumway CL, Motlagh M, Wade M. Anatomy, Head and Neck, Eye Conjunctiva. [Updated 2023 Aug 28]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2026 Jan. Available from: https://www.ncbi.nlm.nih.gov/books/NBK519502/

  • Standring, S. (Ed.). (2015). Eye (Chapter 42). In Gray's anatomy: The anatomical basis of clinical practice (41st ed., pp. ). Churchill Livingstone.

Gallery