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Conjunctivitis, commonly referred to as “red eye” or “pink eye,” is a nonspecific term used to describe an inflammation of the conjunctiva, which can be caused by a wide range of conditions. The conjunctivae are the mucous membranes extending from the eyelid margin to the corneal limbus, forming the posterior layer of the eyelids and the anterior layer of the eyeball. Conjunctivitis may result from primary involvement of the conjunctival tissue or may occur as a secondary manifestation of other ocular or systemic conditions that produce conjunctival inflammation.

Conjunctivitis is prevalent worldwide. It is the most common ocular infection in childhood, usually affecting children younger than 6 years, with a peak incidence between 12 and 36 months.1 Infectious causes of conjunctivitis may be sporadic or related to epidemic outbreaks. In most cases, conjunctivitis is benign and self-limited.

The conjunctiva is a loose connective tissue that covers the surface of the eye (bulbar conjunctiva) and forms the inner layer of the eyelids (palpebral conjunctiva). It is adherent to the underlying sclera at the limbus (corneal margin). It also contains numerous goblet cells, which secrete the mucinous layer of the tear film. Conjunctivitis is characterized by dilatation of the superficial conjunctival blood vessels, resulting in hyperemia and edema of the conjunctiva, with discharge. Fluid may accumulate beneath the loosely attached bulbar conjunctiva, causing it to swell away from the globe, making eye closure difficult (a phenomenon known as chemosis).

Patient History

The diversity of etiologies for conjunctivitis makes a detailed patient history the most important step in the differential diagnosis of conjunctivitis. The patient history should include the chief complaint such as itching, burning, tearing, discharge, pain, foreign body sensation, and photophobia. It should also include questions about the onset and course of the disease, whether it is acute or chronic and progressive or stationary. The ocular history should include questions about previous episodes, prior exposure to infected individuals, history of trauma or contact lens wear, and the use of topical legend (i.e., prescription) or over-the-counter medications or cosmetics. The general health history should include descriptions of recent upper respiratory tract infections, autoimmune disorders, atopy, skin conditions, and sexually transmitted infections. Finally, the social history such as environmental exposure and the family history of ocular diseases may contribute to the diagnosis of “red eye.”

The signs and symptoms of conjunctivitis, including redness, tearing or discharge, and foreign body sensation, are similar regardless of the cause. Pain and photophobia are not symptoms of conjunctivitis; if present, they may indicate other entities, including corneal abrasion, keratitis, uveitis, or acute angle-closure glaucoma. Decreased vision is not typical in patients with conjunctivitis. Occasionally, extensive discharge may blur the visual axis intermittently, but, in general, a report of decreased acuity should prompt a search for more serious disorders.

Physical Examination

The ocular examination in a patient with conjunctivitis ...

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