Most Common Type of Conjunctivitis in Adults
Viral conjunctivitis is the most common overall cause of infectious conjunctivitis in adults, with adenovirus being the predominant pathogen. 1
Epidemiology and Clinical Context
- Viral conjunctivitis accounts for the majority of infectious conjunctivitis cases presenting in primary care settings, though bacterial conjunctivitis is the second most common cause. 1
- Among viral causes, adenovirus is responsible for most cases, often presenting as epidemic keratoconjunctivitis or pharyngoconjunctival fever. 2, 3
- Allergic conjunctivitis affects up to 40% of the population but only a small proportion seek medical attention, making it less commonly diagnosed in clinical practice despite high prevalence. 1
Distinguishing Viral from Other Types
Key features that identify viral conjunctivitis include:
- Watery to serofibrinous discharge (not purulent or mucopurulent). 2, 3, 4
- Follicular reaction on the inferior tarsal conjunctiva with bulbar conjunctival injection. 3
- Bilateral presentation (though may start unilaterally before progressing). 2, 3
- Preauricular or periauricular lymphadenopathy is frequently present. 2, 3
- Recent exposure to infected individuals, particularly in school or household settings. 3
- Associated upper respiratory symptoms may be present, especially in pharyngoconjunctival fever. 2, 3
Comparison with Bacterial Conjunctivitis
While bacterial conjunctivitis is the second most common infectious cause, it differs significantly:
- Purulent or mucopurulent discharge with eyelids matted shut upon waking characterizes bacterial cases. 3, 4
- Absence of prominent follicles distinguishes bacterial from viral etiology. 3
- Bacterial conjunctivitis is more common in children, whereas viral and allergic forms predominate in adults. 4
Clinical Management Implications
For viral conjunctivitis (the most common type):
- Treatment is supportive only: artificial tears, cold compresses, and topical antihistamines for symptomatic relief. 3, 1
- Topical antibiotics are not indicated as viral conjunctivitis does not respond to antibacterial agents. 3
- Symptoms typically improve within 5-14 days. 2, 3
- Strict hygiene measures including frequent handwashing are essential to prevent transmission. 3, 4
Critical Pitfall to Avoid
Always examine the cornea with fluorescein staining in any case of conjunctivitis to detect early corneal involvement, particularly to rule out sight-threatening conditions like gonococcal conjunctivitis (which can cause perforation within 24-48 hours) or progression to epidemic keratoconjunctivitis with subepithelial infiltrates. 5, 3