What are the must-not-miss diagnoses in conjunctivitis?

Must-Not-Miss Diagnoses in Conjunctivitis

The critical must-not-miss diagnoses in conjunctivitis are gonococcal conjunctivitis (which can cause corneal perforation within 24-48 hours), chlamydial conjunctivitis (particularly in neonates and sexually active adults), and any conjunctivitis with corneal involvement, as these carry significant risk for vision loss, systemic complications, and even death if untreated. 1

Life-Threatening and Vision-Threatening Conditions

Gonococcal Conjunctivitis

• This is the single most urgent diagnosis to identify due to rapid progression to corneal perforation, which can occur within hours to days 1
• Presents with marked eyelid edema, severe bulbar conjunctival injection, copious purulent (hyperpurulent) discharge, and preauricular lymphadenopathy 1
• The critical sign to detect is corneal infiltrate or ulcer, which typically begins superiorly 1
• In neonates: manifests 1-7 days after birth and can lead to septicemia with arthritis, meningitis, corneal perforation, and death 1
• In adults: associated with urethritis, pelvic inflammatory disease, septicemia, and arthritis 1
• Requires immediate systemic antibiotics in addition to topical therapy—topical treatment alone is insufficient 2, 3
• In children, consider sexual abuse as a predisposing factor 1

Chlamydial Conjunctivitis (Inclusion Conjunctivitis)

• Frequently missed because it is often indistinguishable from other forms of conjunctivitis on clinical grounds alone 4, 5
• Patients typically see 3 or more doctors before diagnosis is established, with diagnostic delays averaging 15-29 days 5
• In neonates: presents 5-19 days after birth with eyelid edema, purulent/mucopurulent or blood-stained discharge, and NO follicles initially 1
• Up to 50% of infected neonates develop associated nasopharyngeal, genital, or pulmonary infections 1
• In adults: presents with follicular conjunctivitis, with the distinctive sign being follicles on the bulbar conjunctiva and semilunar fold 1
• Nasopharyngeal colonization occurs in 77% of children and 58% of adults 5
• In adults, 77% have positive genital samples for Chlamydia trachomatis even without genital symptoms 5
• Requires systemic antibiotics—topical therapy alone is inadequate 4, 2, 3
• The incidence is rising annually and correlates with increasing genital chlamydia infections 6

Chlamydial Trachoma

• Caused by C. trachomatis serotypes A, B, and C 1
• This is the leading infectious cause of global blindness 1
• Presents with chronic follicular conjunctivitis, corneal pannus, and preauricular lymphadenopathy 1
• Leads to Herbert pits, conjunctival scarring, cicatricial entropion, trichiasis, limbal stem cell deficiency, and corneal opacification 1
• Occurs in low-to-middle income countries without adequate access to clean water and sanitation 1

Serious Systemic Disease Presentations

Parinaud Oculoglandular Syndrome

• Presents with unilateral granulomatous follicular conjunctivitis and ipsilateral regional lymphadenopathy (preauricular and submandibular) 1
• Most commonly caused by cat scratch disease (Bartonella henselae), tularemia (Francisella tularensis), and sporotrichosis 1
• Can lead to neuroretinitis, vitritis, and rarely corneal perforation 1
• Requires systemic workup and treatment for underlying infection 1

Herpes Simplex Virus (HSV) Conjunctivitis

• Can progress to keratitis, stromal keratitis, corneal scarring, perforation, uveitis, and retinitis 1
• Look for vesicular lesions on eyelid margins and dendritic corneal lesions 1
• Primary infection in neonates can be life-threatening with systemic dissemination 1

Varicella Zoster Virus (VZV) Conjunctivitis

• Presents with vesicular dermatomal rash or ulceration of eyelids, often with severe pain 1
• Can cause corneal scarring, uveitis, retinitis, and late corneal anesthesia 1
• Requires systemic antiviral therapy 1

High-Risk Populations Requiring Immediate Attention

Neonates

• Any purulent conjunctivitis in a neonate is an emergency until gonococcal and chlamydial causes are ruled out 1, 3
• Gonococcal infection can lead to septicemia, meningitis, and death 1
• Chlamydial infection causes systemic involvement in 50% of cases 1

Immunocompromised Patients

• Higher risk for severe complications and atypical presentations 1
• Molluscum contagiosum may present with multiple large periocular lesions 1
• Increased susceptibility to opportunistic infections 1

Contact Lens Wearers

• Any conjunctivitis in contact lens wearers should be treated with antibiotics due to risk of Pseudomonas and other serious bacterial infections 2
• Higher risk for corneal involvement and complications 7

Critical Clinical Pitfalls to Avoid

• Do not rely on clinical features alone to distinguish bacterial from viral or chlamydial conjunctivitis—the presentations overlap significantly 4, 2, 5
• Always examine the cornea with fluorescein staining in any case of purulent conjunctivitis to detect early corneal involvement 1
• Consider sexual abuse in children with gonococcal or chlamydial conjunctivitis 1
• Screen for genital infection in adults with chlamydial conjunctivitis—most are asymptomatic genitally 5
• Do not use topical antibiotics alone for gonococcal or chlamydial conjunctivitis—systemic therapy is mandatory 4, 2, 3
• Patients should not wear contact lenses during any episode of bacterial conjunctivitis 8
• The recent increase in gonococcal conjunctivitis (20% of sexually transmitted bacterial conjunctivitis cases in 2006) means this diagnosis must be considered in all cases of purulent conjunctivitis 6