Conjunctivitis

Conjunctivitis, commonly known as pink eye, is an inflammation of the conjunctiva, the outermost layer of the white part of the eye and the inner surface of the eyelid. It manifests as a reddish or pink eye with symptoms that may include pain, burning, scratchiness, or itchiness.

The affected eye might have increased tears or be "stuck shut" in the morning due to discharge. Conjunctivitis can affect one or both eyes and is a frequent cause of eye redness.

Signs and Symptoms

Viral Conjunctivitis

Viral conjunctivitis is often associated with an upper respiratory tract infection, a common cold, or a sore throat. Symptoms include excessive watering and itching, and the discharge is usually watery. The condition typically starts in one eye and can spread to the other. Pre-auricular lymph node swelling may also be present.

Allergic Conjunctivitis

Allergic conjunctivitis is caused by allergens such as pollen, animal hair, or dust mites. Symptoms include redness due to vasodilation, conjunctival swelling, itching, and increased tear production.

Bacterial Conjunctivitis

Bacterial conjunctivitis is common in children and is characterised by rapid onset of redness, eyelid swelling, and a sticky discharge. It often starts in one eye and can spread to the other. The discharge is typically greyish or yellowish and may cause the eyelids to stick together, especially after sleep.

Causes

Conjunctivitis can be caused by viruses, bacteria, allergies, chemical exposure, or autoimmune conditions. Viral conjunctivitis is most commonly caused by adenoviruses. Bacterial conjunctivitis is often due to Staphylococcus aureus, Streptococcus pneumoniae, and Haemophilus influenzae. Allergic conjunctivitis is triggered by allergens like pollen or dust mites.

Diagnosis

Diagnosis is typically based on clinical signs and symptoms. Cultures may be taken if bacterial conjunctivitis is suspected but does not respond to initial treatment. Patch tests can identify allergens in allergic conjunctivitis. Conjunctival scrapes for cytology are rarely performed due to cost and the need for specialised laboratory staff.

Treatment

Treatment of conjunctivitis depends on the underlying cause:

Viral Conjunctivitis

Viral conjunctivitis usually resolves on its own without specific treatment. Antihistamines or mast cell stabilisers may alleviate symptoms.

Allergic Conjunctivitis

Treatment includes the use of cool water to alleviate symptoms and artificial tears. Nonsteroidal anti-inflammatory medications and antihistamines may be prescribed for more severe cases. Persistent allergic conjunctivitis may require topical steroid drops.

Bacterial Conjunctivitis

Bacterial conjunctivitis often resolves without treatment. Topical antibiotics may be used if there is no improvement after three days. Antibiotics are recommended for individuals who wear contact lenses, are immunocompromised, or have a fair amount of pain or copious discharge.

Chemical Conjunctivitis

Chemical conjunctivitis requires immediate irrigation with Ringer's lactate or saline solution. Chemical injuries, especially alkali burns, are medical emergencies and need prompt treatment to prevent severe scarring and intraocular damage.

Epidemiology

Conjunctivitis is the most common eye disease, with acute forms frequently affecting infants, school-age children, and the elderly. Viral conjunctivitis is the most prevalent form, with an estimated 6 million cases annually in the United States. Seasonal trends show bacterial conjunctivitis peaks from December to April, viral conjunctivitis peaks in the summer, and allergic conjunctivitis is more common in spring and summer.

Recent Outbreak

In September 2023, Pakistan experienced a significant outbreak of conjunctivitis, with over 86,133 cases reported in Punjab alone, leading to the temporary closure of schools.

Society and Culture

Conjunctivitis has significant economic and social impacts. The cost of treating bacterial conjunctivitis in the United States ranges from $377 million to $857 million annually. Approximately 1% of all primary care visits are related to conjunctivitis.

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Self-assessment MCQs (single best answer)

What is the common name for conjunctivitis?

Which of the following is NOT a common symptom of conjunctivitis?

What often causes viral conjunctivitis?

Which type of conjunctivitis is characterised by a fine, diffuse pinkness of the conjunctiva and is often associated with an upper respiratory tract infection?

What is the primary symptom differentiating allergic conjunctivitis from other types?

Which bacteria is NOT commonly associated with bacterial conjunctivitis?

How is chemical conjunctivitis typically treated?

In which season does bacterial conjunctivitis peak in the United States?

Which demographic is most frequently affected by acute forms of conjunctivitis?

What was the significant recent event related to conjunctivitis in Pakistan in 2023?