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Infectious conjunctivitis

Background

Overview

Definition
Infectious conjunctivitis is the inflammation of the conjunctiva caused by bacterial, viral, or fungal pathogens.
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Pathophysiology
Viruses account for 80% of all cases of acute conjunctivitis, with most cases caused by adenoviruses. Other viral causes include HSV, VZV, EBV, influenza, enterovirus, and coxsackievirus. Bacterial conjunctivitis is commonly caused by S. aureus, S. pneumoniae, and H. influenzae. Ophthalmia neonatorum is typically caused by C. trachomatis or N. gonorrhoeae. Fungal conjunctivitis is rare and usually occurs in immunocompromised patients.
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Epidemiology
It is estimated that approximately 6 million cases of acute conjunctivitis occur annually in the US.
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Risk factors
Risk factors include close contact with infected individuals, poor hand hygiene, use of contaminated contact lenses, and exposure to contaminated water.
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Disease course
Clinically, infectious conjunctivitis presents with redness, itching, tearing, discharge, and crusting. Bacterial conjunctivitis often presents with purulent discharge, while viral conjunctivitis usually has a watery discharge and may be associated with upper respiratory tract infection symptoms. Fungal conjunctivitis may present with chronic, indolent symptoms.
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Prognosis and risk of recurrence
Most cases of infectious conjunctivitis are self-limiting, lasting 1-2 weeks. Mild bacterial conjunctivitis typically resolves spontaneously without specific treatment in immunocompetent adults.
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Guidelines

Key sources

The following summarized guidelines for the evaluation and management of infectious conjunctivitis are prepared by our editorial team based on guidelines from the American Academy of Family Physicians (AAFP 2024), the American Academy of Ophthalmology (AAO 2024,2019), the College of Optometrists (CO 2023,2022), the Center for Disease Control (CDC 2021), and the U.S. Preventive Services Task Force (USPSTF 2019).
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Diagnostic investigations

History and physical examination
As per AAFP 2024 guidelines:
Elicit a comprehensive eye history and perform a specific physical examination to distinguish bacterial from viral conjunctivitis, recognizing that no single sign or symptom reliably differentiates them.
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Recognize that pain with pupillary constriction (true photophobia), vision change, and anisocoria suggest serious eye disease and require immediate referral.
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Medical management

Setting of care: as per AAO 2019 guidelines, manage most patients with conjunctivitis in an outpatient setting.
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  • Topical antibiotics

  • Topical corticosteroids

  • Topical antihistamines

Nonpharmacologic interventions

Eye hygiene: as per AAFP 2024 guidelines, counsel patients with viral conjunctivitis to avoid touching the face, practice strict handwashing, and refrain from sharing personal items, especially towels, pillowcases, and eye makeup.
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Specific circumstances

Neonatal patients, prevention: as per AAO 2024 guidelines, administer single-use tube erythromycin 0.5% ophthalmic ointment as the standard prophylactic agent for the prevention of ophthalmia neonatorum.
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  • Neonatal patients (setting of care)

  • Neonatal patients (management)

  • Patients with gonococcal conjunctivitis (setting of care)

  • Patients with gonococcal conjunctivitis (antibiotic therapy)