Your cart is currently empty!
M01.10.18 Conjunctiva
The conjunctiva is a thin, translucent, and vascularized mucous membrane covering the anterior part of the sclera and the inner surface of the eyelids. Its structure plays a critical role in protecting the eye and maintaining ocular surface homeostasis.
Layers of the Conjunctiva
The conjunctiva consists of three layers:
- Epithelium
- Type: Non-keratinized stratified columnar epithelium with interspersed goblet cells.
- Goblet Cells: Responsible for secreting mucin, a component of the tear film that aids in ocular surface lubrication.
- Specialization: Near the limbus, the epithelium transitions to stratified squamous epithelium, which is more resistant to mechanical stress.
- Substantia Propria (Lamina Propria)
- Composition: Loose connective tissue containing blood vessels, lymphatics, and immune cells (lymphocytes, plasma cells, mast cells).
- Function: Provides structural support and serves as a site for immune surveillance.
- Subconjunctival Tissue (only in the bulbar conjunctiva)
- Composition: Loose connective tissue that allows movement over the sclera.
- Contains: Accessory lacrimal glands (e.g., glands of Krause and Wolfring), which contribute to tear production.
High power microscopic
Types of Conjunctiva
The conjunctiva is divided into three regions based on its anatomical location:
- Palpebral Conjunctiva: Lines the inner surface of the eyelids.
- Forniceal Conjunctiva: Forms the junction between the palpebral and bulbar conjunctiva; it has the highest density of goblet cells.
- Bulbar Conjunctiva: Covers the anterior part of the sclera up to the corneal limbus.
Histological Features and Clinical Correlation
| Histological Feature | Clinical Relevance |
|---|---|
| Goblet cells | Reduced in dry eye diseases, leading to insufficient tear film. |
| Rich vascularization | Source of redness in conditions like conjunctivitis. |
| Immune cells in substantia propria | Helps in immune defense but can lead to hypersensitivity reactions. |
Points to Remember
- The conjunctiva contributes to the ocular surface’s immune defense and lubrication.
- Goblet cells are critical for maintaining the tear film’s mucin layer.
- The conjunctiva’s vascular supply is essential for nourishment and immune cell trafficking.
Bibliography
- Young B, et al. Wheater’s Functional Histology: A Text and Colour Atlas. Elsevier.
- Kanski JJ, Bowling B. Kanski’s Clinical Ophthalmology: A Systematic Approach. Elsevier.