Initial Approach to Unilateral Conjunctivitis
The initial approach to unilateral conjunctivitis must prioritize immediate identification of vision-threatening and life-threatening causes—particularly gonococcal infection (which can perforate the cornea within 24-48 hours), herpes simplex virus, and any purulent discharge—before considering benign self-limited viral or allergic etiologies. 1
Immediate Red Flags Requiring Urgent Action
Vision-Threatening Conditions
Gonococcal conjunctivitis: Look for marked eyelid edema, significant purulent discharge, and preauricular lymphadenopathy 2. The critical sign is any corneal infiltrate or ulcer (often beginning superiorly), which can progress to perforation within 24-48 hours 1. This requires immediate systemic antibiotics plus topical therapy 1.
Herpes simplex virus (HSV): Typically unilateral with vesicular rash or ulceration of eyelids, and distinctive dendritic epithelial keratitis 2. Can progress to stromal keratitis, corneal scarring, perforation, uveitis, and retinitis 1. Bilateral presentation suggests atopic, pediatric, or immunocompromised patients 2.
Always examine the cornea with fluorescein staining in any purulent conjunctivitis to detect early corneal involvement 1.
Critical History Elements to Obtain Immediately
Sexual history and genitourinary symptoms (dysuria, discharge): Gonococcal and chlamydial conjunctivitis require systemic treatment 2. Consider sexual abuse in children with these infections 1.
Immunocompromised status (HIV, chemotherapy, immunosuppressants): Higher risk for severe complications and atypical presentations 2, 1.
Contact lens wear: Requires antibiotic treatment regardless of suspected etiology 3.
Pain severity: Severe pain with vesicular dermatomal rash suggests varicella zoster virus, which can cause corneal scarring, uveitis, and retinitis 2, 1.
Diagnostic Algorithm Based on Clinical Presentation
Purulent Discharge (Thick, Yellow-Green)
- First priority: Rule out gonococcal infection, especially with marked lid edema and rapid onset 2.
- Second consideration: Bacterial conjunctivitis (Haemophilus influenzae, Streptococcus pneumoniae) 4.
- Key distinguishing features: Mattering and adherence of eyelids on waking, lack of itching, no history of prior conjunctivitis 3.
- Management: Immediate fluorescein examination for corneal involvement 1. If gonococcal suspected, initiate systemic antibiotics immediately 1. For uncomplicated bacterial cases, topical antibiotics (polymyxin-bacitracin or erythromycin) shorten disease duration from 8-10 days to 3-5 days 4, 5, 6.
Watery Discharge with Follicular Reaction
- Most likely: Viral conjunctivitis (adenovirus most common) 3, 7.
- Critical examination: Check for preauricular lymphadenopathy, subconjunctival hemorrhage, and follicles on inferior tarsal conjunctiva 2.
- Unilateral presentation: Often becomes sequentially bilateral within days 2. Initial unilateral presentation does not rule out adenovirus 1.
- Management: Supportive care with artificial tears, cold compresses, and topical antihistamines 8. Strict hand hygiene to prevent spread 8, 7. Monitor for progression to epidemic keratoconjunctivitis with subepithelial infiltrates 1.
Follicles on Bulbar Conjunctiva and Semilunar Fold
- Pathognomonic for chlamydial (inclusion) conjunctivitis 2.
- Requires systemic antibiotics in addition to topical therapy 1.
- Associated findings: Corneal pannus, limbal follicles, superficial keratitis 2.
Unilateral Granulomatous Follicular Conjunctivitis with Ipsilateral Lymphadenopathy
- Parinaud oculoglandular syndrome: Most commonly cat scratch disease, tularemia, or sporotrichosis 1.
- Requires systemic workup and treatment 1.
Special Populations Requiring Modified Approach
Neonates
- Any purulent conjunctivitis is an emergency until gonococcal and chlamydial causes are ruled out 1.
- Gonococcal infection manifests within 1-7 days after birth and can lead to septicemia, meningitis, and death 2, 1.
- Chlamydial conjunctivitis manifests 5-19 days after birth with no follicles initially 2.
Immunocompromised Patients
- Higher risk for HSV (can be bilateral), molluscum contagiosum with multiple large periocular lesions, and severe complications 2, 1.
- Lower threshold for aggressive treatment and ophthalmology referral 8.
When to Defer Antibiotic Treatment
Most uncomplicated viral and bacterial conjunctivitis cases are self-limited 3, 4. However, the following require treatment:
- Gonococcal or chlamydial infection 3, 1
- Contact lens wearers 3
- Neonates 1
- Immunocompromised patients 1
- Corneal involvement 1
For uncomplicated bacterial conjunctivitis, delayed antibiotic prescribing (patient fills prescription only if not improving in 2-3 days) has similar symptom control as immediate prescribing 8.