What is the Conjunctiva?
The conjunctiva is a translucent mucous membrane that covers the ocular surface, extending from the mucocutaneous junction at the eyelid margin to the corneal limbus, where it becomes continuous with the corneal epithelium. 1
Anatomical Structure
The conjunctiva comprises two main layers:
- Conjunctival epithelial cells forming the outer surface 1
- Underlying vascular stroma providing blood supply and structural support 1
The membrane is delicate and transparent, allowing visualization of underlying structures while protecting the eye. 2 It forms a loose sheet that permits free eye movement, with firm attachments only at the circular limbus (where sclera meets cornea) and at the eyelids. 2
Functional Roles
The conjunctiva serves multiple critical functions for ocular surface health:
Mucin production through specialized goblet cells that synthesize negatively charged membrane-bound and soluble mucins, rendering hydrophilic properties to the ocular surface and increasing wettability to enable aqueous tears to spread across the eye 1
Protection of the ocular surface from environmental insults and pathogens 3
Contribution to tear film production and maintenance by secreting components that stabilize the tear layer 1
Drug transport pathway serving as a conduit for drug clearance into systemic circulation or transport to deeper ocular tissues, with a larger surface area than the cornea 3
Ion and fluid homeostasis through various transport processes that regulate ions, solutes, and water in the conjunctival surface and tear film 3
Clinical Significance
When inflamed, the condition is termed conjunctivitis, which can result from infectious, allergic, mechanical, or immune-mediated causes. 1 The conjunctiva's rich vascular supply causes visible redness (hyperemia) when inflamed, making conjunctival pathology readily apparent on examination. 1
The conjunctiva extends into the fornices (the deep folds under the upper and lower eyelids), creating a blind sac that can harbor debris or pathogens. 2 This anatomical feature is clinically relevant for examining the full extent of conjunctival disease and for subconjunctival drug delivery approaches. 3