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At a glance

  • The most common causes of conjunctivitis are allergies and bacterial or viral infections.
  • Bacterial conjunctivitis is usually self-limited, but studies have shown the benefits of topical opthalmic antibiotics.
  • Bacterial resistance to all classes of opthalmic antibiotics has been increasing steadily in recent decades.
  • Fluoroquinolones remain the best choice for the treatment of bacterial conjunctivitis.

Family practice clinicians frequently encounter patients with acute infective conjunctivitis. Approximately 4 million cases of bacterial conjunctivitis are seen annually in the United States in children and adults.1 Almost 25% of infectious conjunctivitis cases occur in children up to age 11 years, with children younger than age 1 year accounting for a greater percentage of cases than any other age group.2

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The total cost of bacterial conjunctivitis in the United States has been estimated to be as much as $857 million annually. This estimate includes direct costs — the value of goods and services used in treatment and management — and indirect costs, which include the economic losses from illness, injury-related work disability, premature death, and time lost from work and leisure activities by caregivers.1

Making the diagnosis

Allergies and bacterial or viral infections are the most common causes of conjunctivitis.3 A presumptive diagnosis can be made by taking a comprehensive patient history and evaluating presenting symptoms. Suggested questions to ask during a diagnostic workup include:

  • When was the onset of symptoms?
  • Was the onset sudden or gradual?4
  • What is the duration of symptoms? Are they chronic or recurrent?5
  • Are symptoms unilateral or bilateral?3,6
  • What is the type and amount of ocular discharge?5,6
  • Is there any ocular pain, photophobia, or blurry vision?5,6
  • Has the patient been in contact with anyone with conjunctivitis?5
  • Are there such allergy symptoms as itching?
  • Does the patient have a history of allergic rhinitis?3,7
  • Has the patient had any recent symptoms of an upper respiratory infection?3

The clinician should also obtain a medication history, including the patient’s use of OTC therapies, eye drops and herbal products.4,8

A physical examination can determine visual acuity, visual fields, extraocular movements and pupillary reaction. Eyelids should be examined for crusting, inflammation and tenderness; the conjunctivae should be examined for edema and hyperemia. Evaluate the amount, color, and type of ocular discharge; examine the cornea for clarity; and palpate for regional lymphadenopathy.8

Bacterial conjunctivitis can usually be differentiated by its symptoms from viral and allergic conjunctivitis and other causes of the red eyes common to all of these conditions (Table 1).4-6,9,10

The pathogens most frequently associated with bacterial conjunctivitis include the gram-positive bacteria Staphylococcus aureus, S. epidermidis, and Streptococcus pneumoniae, and the gram-negative bacteria Haemophilus influenzae.9 These bacteria are part of normal lid or nasopharyngeal flora.11 The types of bacteria that cause bacterial conjunctivitis vary by patients’ ages (Table 2).5,9-11 In young children, H. influenzae is the most commonly isolated bacteria, and infections with H. influenzae may occur concurrently with upper-respiratory infections or otitis media. S. aureus is seen most frequently in older children and adults and is the most common cause of bacterial conjunctivitis worldwide.9,11

Although the majority of patients can be safely managed in a family practice, consider other potentially more serious ocular disorders when evaluating a complaint of red eye. Other differential diagnoses include blepharitis, corneal abrasion, foreign body presence, subconjunctival hemorrhage, herpes simplex conjunctivitis, episcleritis, corneal ulcer, keratitis, iritis, glaucoma, chemical burn and scleritis.

Any potentially vision-threatening ocular condition should be referred immediately to an optometrist or ophthalmologist. Such conditions include decreased visual acuity, significant photophobia, hazy cornea, ocular herpes, severe eye pain or abnormalities in the cornea or anterior segment of the eye.5,6,10