How to evaluate and treat unilateral conjunctivitis?

Evaluation and Treatment of Unilateral Conjunctivitis

Begin by determining whether the presentation suggests viral, bacterial, or non-infectious causes through specific clinical features, as unilateral presentation narrows the differential and guides targeted management. 1

Initial Evaluation

Critical History Elements

• Character of discharge: Watery discharge with photosensitivity and pain strongly suggests viral conjunctivitis, while mucopurulent discharge with matted eyelids indicates bacterial etiology 2, 3
• Unilateral vs. bilateral: HSV conjunctivitis is typically unilateral, while adenoviral conjunctivitis often starts unilateral then becomes sequentially bilateral 1
• Presence of pain and photophobia: These indicate corneal involvement and suggest viral causes (particularly adenovirus or HSV) rather than simple bacterial infection 2
• Skin lesions: Vesicular dermatomal rash or eyelid ulceration points to varicella-zoster virus; dome-shaped umbilicated lesions indicate molluscum contagiosum 1
• Sexual history and genitourinary symptoms: Essential for identifying gonococcal or chlamydial conjunctivitis, which require systemic treatment 1
• Contact lens wear: Mandates aggressive management due to risk of severe corneal infection 1

Physical Examination Priorities

• Preauricular lymphadenopathy: Strongly suggests viral (especially adenoviral) or HSV conjunctivitis 1
• Follicular reaction on tarsal conjunctiva: Indicates viral or chlamydial etiology 1
• Corneal examination: Look for epithelial defects, infiltrates, or subepithelial infiltrates that indicate more serious disease requiring ophthalmology referral 2, 4
• Eyelid margin inspection: Check for molluscum lesions or herpetic vesicles 1

Management Algorithm

Viral Conjunctivitis (Most Common)

Supportive care is the primary treatment, as viral conjunctivitis is self-limited and does not benefit from antibiotics or routine antiviral therapy. 2

• Treatment consists of: Artificial tears for symptomatic relief, cold compresses to reduce inflammation, and strict hand hygiene to prevent transmission 2
• Topical antibiotics are NOT indicated and only promote resistance without benefit 2
• Duration: Self-limited with improvement within 5-14 days 1

Exception for HSV: If distinctive signs present (vesicular eyelid lesions, pseudodendritic keratitis), topical antivirals are indicated 2

Bacterial Conjunctivitis

Most uncomplicated bacterial conjunctivitis is self-limited, resolving in 1-2 weeks without treatment. 3

• Clinical features: Mucopurulent discharge, matted eyelids on waking, absence of itching 3
• Topical antibiotics shorten duration by approximately 1 day and allow earlier return to work/school 2, 3
• Options include: Erythromycin ointment applied up to 6 times daily 5 or bacitracin ointment 1-3 times daily 6

Critical exceptions requiring aggressive treatment:

• Gonococcal conjunctivitis: Marked eyelid edema, severe purulent discharge, risk of corneal perforation—requires systemic antibiotics PLUS topical therapy and urgent ophthalmology referral 1
• Chlamydial conjunctivitis: Follicular reaction, requires systemic treatment (not just topical) to address concurrent genitourinary infection 1
• Contact lens wearers: Must be treated with antibiotics due to risk of severe corneal complications 3

Allergic Conjunctivitis

• Key feature: Itching is the most consistent sign 3, 7
• Treatment: Topical antihistamines with mast cell-stabilizing activity are first-line 3, 7
• Severe cases: Loteprednol etabonate (C-20 ester corticosteroid) provides effective anti-inflammatory relief with improved safety profile compared to traditional corticosteroids 7

Mandatory Ophthalmology Referral

Urgent referral is required for: 2, 4

• Decreased vision
• Severe pain (not just irritation)
• Corneal involvement (infiltrates, ulcers)
• Recent ocular surgery
• Vesicular rash on eyelids or nose (suggests HSV/VZV)
• Immunocompromised state
• Neonatal conjunctivitis
• History of rheumatologic disease

Common Pitfalls

• Prescribing antibiotics for viral conjunctivitis: This promotes resistance without benefit and is the most common error 2, 3
• Missing gonococcal conjunctivitis: Rapid progression to corneal perforation can occur; marked purulent discharge with severe eyelid edema demands immediate aggressive treatment 1
• Failing to obtain sexual history: Chlamydial and gonococcal conjunctivitis require systemic treatment to prevent complications and treat concurrent STIs 1
• Using topical corticosteroids without ruling out HSV: Can worsen herpetic disease; only use after confirming diagnosis 2
• Ignoring contact lens wear: These patients require cultures and aggressive antibiotic management due to risk of devastating corneal complications 1, 3