Conjunctivitis constitutes approximately one half of all eye-related diagnoses seen in primary care offices and nearly one third of all ED visits for ocular problems.
Accurate differentiation between viral, bacterial, allergic, and other causes of acute conjunctivitis can be challenging because all these etiologies can present with similar clinical features.
The overwhelming majority of acute conjunctivitis cases are either allergic or viral in etiology. A bacterial cause is more common in young children than adults. Nevertheless, acute bacterial conjunctivitis is usually mild and self-limiting, often self-resolving within 7-14 days without antibiotic therapy. Although topical antibiotics may hasten resolution of symptoms, this benefit must be weighed against the risk of ocular surface toxicity, antibiotic resistance, and the cost associated with their use.
A 2009 clinical review noted that there is moderate-quality evidence that topical antibiotics are no more effective than placebo at increasing clinical cure rates in people with suspected bacterial conjunctivitis at days 5 to 7.
In 2013, as part of the nationwide “Choosing Wisely” initiative to reduce wasteful or unnecessary medical testing and treatment, the American Academy of Ophthalmology recommended avoiding antibiotic prescriptions for viral conjunctivitis and deferring immediate antibiotic therapy when the etiology of conjunctivitis is unknown.
A 2017 study of over 340k patients diagnosed with acute conjunctivitis found that nearly 60% filled ≥1 topical antibiotic prescription. Compared to patients diagnosed by ophthalmologists, enrollees had considerably higher odds of antibiotic prescription fills if first diagnosed by optometrists (OR:1.26, CI:1.21–1.31), urgent care physicians (OR:3.29, CI:3.17–3.41), internists (OR:2.79, CI:2.69–2.90), pediatricians (OR:2.27, CI:2.13–2.43), or family practitioners (OR:2.46, CI:2.37–2.55).
Accordingly, the American Academy of Ophthalmology’s 2018 Preferred Practice Patterns on treating acute conjunctivitis includes the following statement: “Indiscriminate use of topical antibiotics or corticosteroids should be avoided. Viral conjunctivitis will not respond to anti-bacterial agents, and mild bacterial conjunctivitis is likely to be self-limited. No evidence exists demonstrating the superiority of any topical antibiotic agent.”
Nevertheless, there is some evidence to the contrary. For instance, earlier this year, a Cochrane review entitled “Antibiotics versus placebo for acute bacterial conjunctivitis” found the use of topical antibiotics likely improved clinical cure (resolution of clinical symptoms or signs) by 26% as compared with placebo.