Conjunctiva

Diagram of the human eye, showing the conjunctiva.

The conjunctiva is a thin, transparent mucous membrane that covers the sclera (the white part of the eye) and lines the inside of the eyelids. It plays a crucial role in maintaining the health of the eye by providing a protective barrier against environmental irritants and pathogens.

Anatomy

The conjunctiva is divided into three parts:

• Palpebral conjunctiva: This part lines the inside of the eyelids. It is highly vascularized and adheres tightly to the tarsal plates of the eyelids.
• Bulbar conjunctiva: This part covers the anterior surface of the sclera, up to the cornea. It is loosely attached to the underlying tissue, allowing for free movement of the eyeball.
• Fornix conjunctiva: This is the loose, flexible fold that connects the palpebral and bulbar conjunctiva, allowing for the movement of the eye and eyelids.

Close-up of the human eye showing the conjunctiva.

Function

The primary functions of the conjunctiva include:

• Protection: It acts as a barrier to dust, debris, and microorganisms, preventing them from entering the eye.
• Lubrication: The conjunctiva produces mucus and tears, which help to keep the eye moist and facilitate smooth movement of the eyelids over the eyeball.
• Immune defense: It contains immune cells that help to detect and respond to pathogens.

Clinical Significance

Conjunctival hyperemia, a common sign of conjunctivitis.

The conjunctiva can be affected by various conditions, including:

• Conjunctivitis: Also known as "pink eye," this is an inflammation of the conjunctiva, often caused by infections, allergies, or irritants.
• Pterygium: A benign growth of the conjunctiva that can extend onto the cornea, potentially affecting vision.
• Pinguecula: A yellowish, benign growth on the conjunctiva, usually on the side closest to the nose.

Histology

Histological section of the conjunctiva.

The conjunctiva is composed of a non-keratinized stratified columnar epithelium with goblet cells interspersed throughout. These goblet cells are responsible for secreting mucus, which contributes to the tear film and helps maintain ocular surface health.

Related Pages

• Eye
• Cornea
• Sclera
• Tear film

Histological slide showing conjunctival tissue.

See Also

• Ophthalmology
• Visual system
• Mucous membrane

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