Author: Dr Julie Fraser, Adelaide, Australia. Chief Editor: Dr Amanda Oakley, Dermatologist, Hamilton, New Zealand, December 2015.

What is conjunctivitis?

Conjunctivitis is inflammation of the conjunctiva of the eye.

The conjunctiva is the semi-transparent membrane that covers the white part of the eye (the sclera) and lines the inside of the eyelids.

When the conjunctiva is inflamed, the white of the eye appears red. Conjunctivitis is the most likely diagnosis when a patient has a red eye and discharge.

What causes conjunctivitis?

Acute conjunctivitis can be either infectious or non-infectious. Conjunctivitis due to infectious causes is highly contagious: spread is by direct contact with the patient, their secretions or contaminated surfaces.

Infectious causes

Non-infectious causes

What are the symptoms and signs of conjunctivitis?

Conjunctivitis is a diagnosis of exclusion. All forms of conjunctivitis are characterised by:

The following "red flags" point to other more serious diagnoses, such as keratitis (inflammation of the cornea), iritis, or angle closure glaucoma:

What are the complications of conjunctivitis?

Most forms of conjunctivitis are self-limiting but in certain cases, severe complications may occur. Pain, loss of vision or photophobia require immediate referal to an opthalmologist.

Complications from conjunctivitis include:

Conjunctivitis caused by Neisseria meningitidis (meningococcus) can precede meningitis.

How is conjunctivitis treated?

Many cases of infectious conjunctivitis resolve spontaneously within 14 days. Treatment in mild cases is mainly symptomatic with patient education regarding hygiene to prevent its spread.

Glucocorticoids should only be used under specialist advice to avoid sight-threatening complications.

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