- The conjunctiva is a thin, transparent mucous membrane that lines the inner surface of the eyelids and covers the anterior portion of the sclera, the white part of the eye, up to the edge of the cornea. This membrane plays a critical role in protecting the eye, maintaining ocular surface health, and facilitating smooth eyelid movement. Despite its delicate structure, the conjunctiva serves as a first line of defense against environmental irritants, allergens, and pathogens.
- Anatomically, the conjunctiva is divided into three regions:
- Palpebral conjunctiva – lines the inner surface of the upper and lower eyelids.
- Forniceal conjunctiva – forms a loose fold that connects the palpebral and bulbar portions, allowing free movement of the eye.
- Bulbar conjunctiva – covers the exposed anterior surface of the sclera and merges with the corneal epithelium at the limbus.
- The conjunctiva consists of an epithelial layer, which contains goblet cells responsible for secreting mucin, a key component of the tear film that lubricates and protects the eye, and a stromal layer rich in blood vessels, lymphatics, and immune cells. Its vascular supply makes it highly responsive to inflammation and infection, which is why redness is a common sign of conjunctival irritation.
- Functionally, the conjunctiva provides a protective barrier and supports the immune surveillance of the eye. It traps and flushes away debris and microbes with the aid of tears and mucin, and hosts immune cells that respond to pathogens. It also maintains hydration of the ocular surface, ensures proper spread of tears during blinking, and contributes to the healing of minor injuries.
- Several disorders can affect the conjunctiva, the most common being conjunctivitis, or inflammation of the conjunctiva. Conjunctivitis may be caused by infections (bacterial, viral), allergies, or irritants such as smoke or chemicals. Symptoms typically include redness, itching, tearing, discharge, and a gritty or burning sensation in the eyes. Viral conjunctivitis is highly contagious, especially in crowded environments such as schools or workplaces. Allergic conjunctivitis, often associated with seasonal allergies, can cause intense itching and swelling.
- Other conditions involving the conjunctiva include pinguecula (a yellowish, raised area on the sclera near the cornea), pterygium (a fibrovascular growth that can extend onto the cornea), subconjunctival hemorrhage (a bright red patch due to a broken blood vessel), and conjunctival tumors, which may be benign or malignant. Chronic inflammation or irritation can also lead to conjunctival scarring, which may impair eye movement or tear film stability.
- Diagnosis of conjunctival conditions is generally clinical and based on history, symptoms, and eye examination using a slit lamp. Swab cultures or cytology may be needed to identify infectious agents or rule out more serious pathology. Treatment depends on the underlying cause and may involve antibiotic or antiviral drops, antihistamines, lubricants, or anti-inflammatory medications.
