What are the differences in treatment and management between viral, bacterial, and allergic conjunctivitis?

Differentiating Viral, Bacterial, and Allergic Conjunctivitis

Viral conjunctivitis presents with watery discharge and follicular reaction, bacterial conjunctivitis shows mucopurulent discharge with matted eyelids and papillary reaction, while allergic conjunctivitis is distinguished by itching as the predominant symptom. 1

Clinical Presentation: Key Distinguishing Features

Viral Conjunctivitis

• Discharge type: Watery, clear discharge 1, 2
• Onset pattern: Abrupt onset, often starts unilateral but becomes sequentially bilateral within days 1
• Conjunctival reaction: Follicular pattern on inferior tarsal conjunctiva (small, raised bumps) 1, 3
• Associated findings: Preauricular lymphadenopathy (swollen lymph node in front of ear), often with concurrent upper respiratory infection 1
• Additional signs: Subconjunctival hemorrhages, chemosis (conjunctival swelling), eyelid swelling and erythema may be present 1
• Duration: Self-limited, typically resolves within 5-14 days without treatment 1

Bacterial Conjunctivitis

• Discharge type: Purulent or mucopurulent (thick, yellow-green) discharge with eyelids matted shut upon waking 1, 2
• Presentation: Can be unilateral or bilateral 1
• Conjunctival reaction: Papillary reaction (not follicular) - appears as a velvety, bumpy surface 1
• Associated findings: Preauricular lymphadenopathy is less common unless caused by hypervirulent organisms like gonococcus 1
• Concurrent infections: May be associated with bacterial otitis media, sinusitis, or pharyngitis, particularly in children 1

Allergic Conjunctivitis

• Hallmark symptom: Itching is the most consistent and distinguishing feature 3, 2
• Discharge type: Watery discharge 2
• Pattern: Bilateral presentation, often seasonal or perennial depending on allergen exposure 4
• Associated symptoms: May have concurrent allergic rhinitis or asthma 4
• Absence of: No preauricular lymphadenopathy, no matted eyelids 1

Treatment Approach by Etiology

Viral Conjunctivitis Management

Antibiotics should be avoided entirely for viral conjunctivitis as they provide no benefit and may cause toxicity. 1

• Supportive care only: Artificial tears for symptomatic relief and to dilute viral particles on ocular surface 1, 5
• Cold compresses: Reduce inflammation and provide comfort 5
• Topical antihistamines: May help alleviate itching and discomfort 1, 5
• Oral analgesics: For pain management if needed 5
• Patient education critical: Highly contagious - minimize contact with others for 10-14 days from symptom onset in last affected eye 1, 5
• Hygiene measures: Frequent handwashing, avoid sharing towels/pillowcases, disinfect surfaces 1, 5

Severe cases requiring corticosteroids: For severe adenoviral keratoconjunctivitis with pseudomembranes or subepithelial infiltrates causing vision impairment, topical corticosteroids may be considered, but require close ophthalmology follow-up for monitoring intraocular pressure and cataract formation 5

• Critical caveat: Corticosteroids may prolong viral shedding and can worsen HSV infections 4, 5
• If used: Prefer corticosteroids with poor ocular penetration, taper slowly to minimum effective dose 5

Special viral types requiring different management:

• HSV conjunctivitis: Consider ganciclovir 0.15% gel, trifluridine 1% solution, or oral antivirals; avoid corticosteroids 5
• VZV conjunctivitis: Oral antivirals (acyclovir 800 mg five times daily for 7 days, valacyclovir 1000 mg every 8 hours for 7 days, or famciclovir 500 mg three times daily for 7 days) for persistent cases; topical antibiotics to prevent secondary bacterial infection 4, 5
• Molluscum contagiosum: Remove causative eyelid lesions via incision and curettage, excision, or cryotherapy 4, 5

Bacterial Conjunctivitis Management

Mild bacterial conjunctivitis is usually self-limited and resolves spontaneously without treatment, but topical antibiotics shorten duration and allow earlier return to school or work. 4, 1

• Mild cases: 5-7 day course of broad-spectrum topical antibiotic applied 4 times daily 4, 6
• No superiority of specific agents: Choose most convenient or least expensive option - fluoroquinolones (moxifloxacin, gatifloxacin) or aminoglycosides (tobramycin) are effective 4, 6, 7
• Dosing example: Moxifloxacin 0.5% - one drop in affected eye 3 times daily for 7 days 7

Moderate to severe bacterial conjunctivitis (copious purulent discharge, pain, marked inflammation):

• Obtain cultures: Conjunctival cultures and Gram staining before initiating treatment, especially if gonococcal infection suspected 4, 6
• Broad-spectrum topical antibiotics: Same 5-7 day course as mild cases 4, 6
• Follow-up timing: Return if no improvement after 3-4 days of treatment 6

Special considerations:

• Gonococcal conjunctivitis: Requires systemic treatment in addition to topical therapy; can lead to corneal perforation 1, 3
• Chlamydial conjunctivitis: Requires systemic treatment and evaluation of sexual partners 1
• MRSA increasing: Methicillin-resistant Staphylococcus aureus isolated with increasing frequency; fluoroquinolones remain effective 4

Allergic Conjunctivitis Management

Topical antihistamines with mast cell-stabilizing activity are first-line treatment for allergic conjunctivitis. 1, 2

• Environmental modifications: Wear sunglasses as barrier to airborne allergens, use cold compresses, refrigerated artificial tears, avoid eye rubbing 4, 1
• First-line pharmacologic: Second-generation topical histamine H1-receptor antagonists with mast cell-stabilizing properties 4
• Mild cases: Over-the-counter topical antihistamine/vasoconstrictor agents acceptable 4
• Chronic/recurrent cases: Mast-cell stabilizers for prevention 4
• Refrigeration tip: Store topical medications in refrigerator for additional cooling comfort upon instillation 4

Refractory cases:

• Short-term corticosteroids: Brief 1-2 week course of topical corticosteroids with low side-effect profile if symptoms not adequately controlled 4
• Severe cases: Topical cyclosporine or tacrolimus can be considered 4
• Allergen-specific immunotherapy: Beneficial in reducing symptoms, more effective in children than adults 1

Caution with oral antihistamines: May induce or worsen dry eye syndrome and impair tear film's protective barrier 4

Red Flags Requiring Immediate Ophthalmology Referral

• Visual loss or decreased vision 1
• Moderate to severe pain 2
• Corneal involvement (infiltrates, ulcers) 1
• Conjunctival scarring 1, 5
• Severe purulent discharge (consider gonococcus) 1
• Vesicular rash on eyelids or nose (suggests HSV or VZV) 2
• Lack of response to therapy after 3-4 days 6
• Recurrent episodes 1
• History of HSV eye disease 1
• Immunocompromised state 2
• Recent ocular surgery 2
• Neonatal conjunctivitis (requires prompt evaluation, may need hospitalization) 1

Common Pitfalls to Avoid

• Never use topical corticosteroids indiscriminately: Can prolong adenoviral infections, worsen HSV infections, and cause increased intraocular pressure and cataracts 4, 1
• Avoid contact lens wear: Patients must not wear contact lenses during any form of infectious conjunctivitis 4, 6, 7
• Don't assume all red eyes are benign: Chronic/recalcitrant conjunctivitis may indicate underlying malignancy (sebaceous or squamous cell carcinoma) 1
• Vasoconstrictor rebound: Chronic use of topical vasoconstrictor agents can cause rebound vasodilation once stopped 4
• Inadequate patient education about contagiousness: Failure to educate about viral conjunctivitis transmission leads to community spread 1

Follow-Up Recommendations

• Viral conjunctivitis: Re-evaluate within 1 week if severe; return if symptoms persist beyond 2-3 weeks 5
• Bacterial conjunctivitis: Return if no improvement after 3-4 days of antibiotics 6
• Allergic conjunctivitis on corticosteroids: Regular monitoring of intraocular pressure and pupillary dilation required 1
• All follow-ups should include: Interval history, visual acuity measurement, and slit-lamp biomicroscopy 1, 5