Conjunctivitis

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Conjunctivitis

Conjunctivitis is inflammation of the conjunctiva and is one of the most common causes of the red eye. Most cases are viral and self-limited; the clinical challenge is identifying the occasional serious bacterial infection or herpetic corneal involvement that requires aggressive treatment.

Etiology

Category	Examples
Viral	Adenovirus (most common), HSV, enterovirus, influenza
Bacterial	Staphylococcus, Streptococcus, H. influenzae, N. gonorrhoeae, Chlamydia
Allergic	Environmental allergens, contact lens solutions
Toxic/Chemical	Chlorine, smoke, medications
Parasitic/Fungal	Rare

Types & Clinical Features

1. Bacterial Conjunctivitis

Key features:

Painless, mucopurulent discharge — often causes eyelids to adhere on awakening
Unilateral or bilateral conjunctival injection
Clear cornea (no fluorescein staining)
Chemosis (conjunctival edema) is common
No preauricular lymphadenopathy (except in gonococcal infection)

Bacterial conjunctivitis — mucopurulent discharge, conjunctival injection, lid edema (H. influenzae in a pediatric patient)

Bacterial conjunctivitis: mucopurulent discharge, conjunctival injection, and lid edema

Typical pathogens: Staphylococcus spp., Streptococcus spp.

Special forms:

Gonococcal — can cause ophthalmia neonatorum; associated with preauricular lymphadenopathy
Chlamydial — also a disease of the newborn

Treatment:

Most cases are self-limited, but antibiotics shorten the course
Trimethoprim–polymyxin B — effective first-line; avoids sulfa/neomycin allergy risk
Contact lens wearers: fluoroquinolone (besifloxacin, gatifloxacin, moxifloxacin, ofloxacin) or tobramycin to cover Pseudomonas
Always perform fluorescein staining of the cornea, especially in infants, to rule out abrasion, ulcer, or herpetic dendrite

2. Viral Conjunctivitis

Key features:

URI may precede onset
Watery discharge (not purulent)
Mild-to-moderate red eye; no pain unless keratitis is present
One eye involved first, second eye follows within days
Preauricular lymphadenopathy present
Slit lamp: follicles (small, regular, translucent bumps) on inferior palpebral conjunctiva
Highly contagious

Viral conjunctivitis — bilateral conjunctival injection with watery discharge and lid edema

Viral conjunctivitis: bilateral conjunctival injection, watery discharge, lid edema

Epidemic Keratoconjunctivitis (EKC):

More severe adenovirus variant; occurs in epidemics
Prodrome: cough, high fever, malaise, myalgias
Corneal punctate staining on fluorescein — represents keratitis
Duration: 1–3 weeks

Treatment:

Cool compresses
Ocular decongestants (e.g., Naphcon-A, 1 drop TID PRN)
Artificial tears 5–6×/day
Instruct patient: frequent handwashing, separate towels
Examiner should wear gloves; disinfect slit lamp and furniture after contact

3. Allergic Conjunctivitis

Key features:

Intense itching — hallmark symptom
Watery discharge, redness
Erythematous, swollen eyelids
Injected, edematous conjunctiva with papillae (irregular mounds of tissue with central vascular tuft) on inferior fornix
Chemosis (conjunctival edema) may be prominent

Allergic conjunctivitis — prominent chemosis and chemotic lower conjunctiva

Allergic conjunctivitis: prominent chemosis of the lower palpebral conjunctiva

Treatment (stepwise by severity):

Mild: identify/eliminate allergen; cool compresses QID; artificial tears alone
Moderate: topical antihistamine/decongestant, mast cell stabilizers, or NSAIDs
Severe: topical steroids (consult ophthalmologist first — occult herpetic infection must be excluded)

Key Differentiating Features

Feature	Bacterial	Viral	Allergic
Discharge	Mucopurulent	Watery	Watery
Itch	Absent/mild	Absent/mild	Prominent
Preauricular nodes	Absent (except GC)	Present	Absent
Conjunctival findings	Papillae, chemosis	Follicles	Papillae, chemosis
Laterality	Uni/bilateral	Starts unilateral	Usually bilateral
Associated symptoms	None	URI, fever	Atopy history

When to Refer / Red Flags

Decreased visual acuity
Corneal involvement (fluorescein staining positive) — suspect herpetic dendrite
Severe pain
Gonococcal infection (requires systemic antibiotics)
No improvement after empiric treatment

If bacterial vs. viral is uncertain after assessment, prescribe topical antibiotics pending ophthalmology follow-up.

— Tintinalli's Emergency Medicine: A Comprehensive Study Guide

Treatment

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Here is a comprehensive treatment summary for conjunctivitis, organized by type:

Treatment of Conjunctivitis

1. Bacterial Conjunctivitis

General Principle

About 60% resolve within 5 days without treatment. Antibiotics shorten the course and reduce transmission but are not always mandatory.

Topical Antibiotics (first-line options)

Use QID for up to 1 week. Ointments provide higher concentration and longer contact time but blur vision — reserve for nighttime use.

Agent	Notes
Trimethoprim–polymyxin B	Preferred first-line; avoids sulfa/neomycin allergy risk
Erythromycin / Bacitracin ointment	Broad coverage, well tolerated
Tobramycin	Good gram-positive and gram-negative coverage
Ciprofloxacin / Ofloxacin	Broad-spectrum fluoroquinolones
Gatifloxacin / Moxifloxacin / Besifloxacin	Newer fluoroquinolones; better gram-positive penetration
Chloramphenicol	Widely used outside USA; some practitioners avoid due to rare aplastic anaemia risk
Fusidic acid	Option in some guidelines

Contact lens wearers: Use a fluoroquinolone or tobramycin to cover Pseudomonas.

If no improvement in 2–3 days or worsening, refer to ophthalmologist. Culture discharge in severe cases.

Systemic Antibiotics — Required For:

Organism	Systemic Treatment
N. gonorrhoeae	Ceftriaxone (preferred in adults); quinolones or macrolides are alternatives. Seek genitourinary specialist input
H. influenzae	Oral amoxicillin–clavulanic acid (25% risk of otitis/systemic spread in children)
N. meningitidis	IM benzylpenicillin, ceftriaxone, or cefotaxime — do not delay; up to 30% develop systemic disease
Trachoma	Systemic azithromycin (with specialist consultation)

Gonococcal/meningococcal: Also give topical antibiotic 1–2 hourly initially (quinolone, gentamicin, chloramphenicol, or bacitracin) in addition to systemic therapy.

Supportive

Irrigation with normal saline to clear excessive discharge in hyperpurulent cases
Discontinue contact lenses until 48 hours after complete symptom resolution

2. Viral Conjunctivitis

Largely self-limited (1–3 weeks). No specific antivirals except for herpetic involvement.

Measure	Details
Cool compresses	Several times daily for comfort
Artificial tears	5–6 times/day
Topical decongestant	e.g., Naphcon-A 1 drop TID PRN for redness
Topical antibiotics	Not routinely indicated; prescribe only if bacterial vs. viral distinction is uncertain pending ophthalmology review
Topical steroids	Avoid — prolongs viral infection and risks corneal herpetic penetration

Herpes keratitis (HSV): Topical acyclovir 5% ointment — requires ophthalmology or infectious disease consultation.

Infection Control (critical)

Frequent handwashing; separate towels
Examiner wears gloves; disinfect slit lamp and examination surfaces
No evidence-based medical reason to exclude from school/daycare, though many institutions mandate antibiotics before return

3. Allergic Conjunctivitis

Non-pharmacological

Identify and eliminate the allergen
Cool compresses QID
Keep windows closed during allergy season; wash face/hair after outdoors; avoid touching eyes

Pharmacological (stepwise)

Severity	Treatment
Mild	Artificial tears alone; oral non-sedating antihistamine
Moderate	Topical antihistamine–decongestant (naphazoline–pheniramine [Naphcon-A]) — note: rebound vasodilation can occur with prolonged use
Moderate–Severe	Topical mast cell stabilizer: cromolyn sodium 4%, pemirolast (QID during allergy season); dual-action antihistamine + mast cell stabilizer: olopatadine (Patanol), ketotifen, azelastine (Optivar)
Moderate	Topical NSAIDs: ketorolac (Acular), lodoxamide (Alomide)
Severe	Topical corticosteroids — only with ophthalmology consultation (risk of herpetic infection, glaucoma, cataracts, fungal ulcer)
Refractory	Allergy testing and immunotherapy (desensitization shots)

For concomitant allergic rhinoconjunctivitis: topical cromolyn sodium or topical antihistamines (olopatadine, azelastine, ketotifen, epinastine) are effective.

4. Neonatal Conjunctivitis (Ophthalmia Neonatorum)

Type	Onset	Treatment
Chemical (silver nitrate prophylaxis)	Day 1	None — self-resolves
Gonococcal	Days 3–5	IV/IM cefotaxime 50 mg/kg (preferred over ceftriaxone in neonates — avoids bilirubin displacement and kernicterus); admit + ophthalmology consult; irrigate with NS; topical alone is inadequate
Chlamydial	End of week 1 – 1 month	Oral erythromycin 50 mg/kg/day ÷ QID × 14 days; treat mother and partners; topical unnecessary
HSV	Variable	Full sepsis evaluation; IV acyclovir 20 mg/kg/dose TID

Key Contraindication

Topical corticosteroids should not be used for conjunctivitis outside ophthalmologist supervision due to risk of:

Herpetic corneal perforation
Steroid-induced open-angle glaucoma
Cataracts
Fungal corneal ulcer

— Kanski's Clinical Ophthalmology, Tintinalli's Emergency Medicine, Textbook of Family Medicine 9e, Rosen's Emergency Medicine

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