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Conjunctivitis: A Comprehensive Clinical Analysis

1. Definition and Anatomy

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2. Classification and Etiology

2.1 Infectious

Viral (Most Common)

Symptoms typically resolve spontaneously within 2 weeks; however, certain adenovirus serotypes may cause EKC where symptoms last weeks to months.

• Tietz Textbook of Laboratory Medicine, 7th Ed.

Bacterial

• Staphylococcus aureus (predominates in adults)
• Streptococcus pneumoniae
• Haemophilus influenzae (more common in children)
• Moraxella catarrhalis
• Escherichia coli, Pseudomonas aeruginosa (especially in soft contact lens wearers)

• Neisseria gonorrhoeae - causes hyperacute conjunctivitis with copious thick yellowish-green discharge; can rapidly perforate the cornea; requires systemic antibiotics
• Neisseria meningitidis - less common but serious
• Chlamydia trachomatis - causes inclusion conjunctivitis and trachoma (leading infectious cause of blindness worldwide)

Chlamydial Conjunctivitis (Special Category)

• Inclusion conjunctivitis results from sexually acquired C. trachomatis, causing redness and mucopurulent discharge
• Trachoma (serotypes A, B, Ba, C) is the leading infectious cause of blindness globally. It begins with mild follicular conjunctivitis; repeated infections produce scarring that inverts the upper eyelids (trichiasis), and the eyelashes abrading the cornea ultimately cause corneal ulceration, scarring, and opacification.
• The WHO's SAFE strategy (Surgery for trichiasis, Antibiotics for active infection, Facial cleanliness, Environmental improvement) has brought the at-risk population down to ~142 million (as of 2019).

• Robbins & Kumar Basic Pathology, Tietz Textbook of Laboratory Medicine

2.2 Allergic

• Seasonal allergic conjunctivitis (SAC): Most common; triggered by pollens; bilateral, seasonal
• Perennial allergic conjunctivitis (PAC): Year-round; triggered by dust mites, animal dander
• Vernal keratoconjunctivitis (VKC): Recurrent, seasonal (spring/early summer); more common in young males in warm climates; characteristic cobblestone papillae under the upper lid (see image below)
• Giant papillary conjunctivitis (GPC): Associated with soft contact lens wear; caused by allergy to sterilizing solutions and lens proteins; managed by switching to preservative-free solutions or daily-wear disposable lenses

2.3 Other Causes

• Toxic/Chemical: Exposure to chlorine, smoke, chemicals; also from certain topical medications (gentamicin, neomycin, sulfacetamide can cause toxic chemical conjunctivitis)
• Parasitic/Fungal: Rare
• Neonatal (Ophthalmia Neonatorum): Requires separate evaluation (discussed below)

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3. Clinical Features and Diagnosis

3.1 Key Symptom Comparison

3.2 Visual Findings

3.3 Slit-Lamp Findings

• Follicles (small, regular, translucent bumps on inferior palpebral conjunctiva) - indicate viral or chlamydial etiology
• Papillae (irregular mounds with central vascular tuft) - indicate bacterial or allergic etiology
• Punctate fluorescein staining - indicates keratitis (most commonly in EKC or HSV)
• Chemosis (conjunctival edema) - common in bacterial and allergic types

3.4 Red Flags Requiring Urgent Ophthalmologic Consultation

• Decreased visual acuity
• Severe eye pain (suggests iritis, keratitis, acute glaucoma)
• Photophobia
• Corneal opacity or fluorescein staining (possible herpetic dendrite or corneal ulcer)
• Copious purulent discharge suggestive of gonococcal infection
• Failure to improve after 2 weeks of treatment
• Neonatal conjunctivitis

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4. Special Forms

4.1 Epidemic Keratoconjunctivitis (EKC)

• Caused by adenovirus (particularly serotypes 8, 19, 37)
• Highly contagious; can cause outbreaks in workplaces and healthcare settings
• Systemic symptoms (cough, high fever, malaise, myalgias) may precede ocular involvement
• Corneal subepithelial infiltrates develop, causing photophobia and decreased vision
• Can last weeks to months
• Infection control: examiner must wear gloves, disinfect slit lamp and furniture after each patient contact

4.2 Gonococcal Conjunctivitis

• Hyperacute onset with profuse, thick, purulent discharge within 12-24 hours
• Tender preauricular lymphadenopathy
• High risk of corneal perforation if untreated
• In neonates: presents within 2-5 days of birth (from maternal genital tract)
• Diagnosis: Gram stain shows gram-negative intracellular diplococci; culture on Thayer-Martin medium
• Treatment: systemic antibiotics required (not just topical) - ceftriaxone IV/IM

4.3 Chlamydial (Inclusion) Conjunctivitis in Adults

• Sexually transmitted; inoculation from genital secretions to eye
• Follicular conjunctivitis; chronic and persistent if untreated
• Treated with oral azithromycin or doxycycline (systemic treatment, as topical alone is insufficient)

4.4 Herpes Simplex Conjunctivitis

• Presents as unilateral follicular conjunctivitis
• Look for conjunctival dendrites or geographic ulceration
• Critical: always stain with fluorescein to detect herpetic dendrite in the cornea - a branching linear ulceration with club-shaped terminal bulbs at each branch end
• Treatment: topical antivirals (trifluridine, ganciclovir gel) or oral acyclovir/valacyclovir
• Avoid topical steroids without ophthalmologic consultation - can dramatically worsen HSV infection

4.5 Ophthalmia Neonatorum (Neonatal Conjunctivitis)

• Prevention: neonatal ocular prophylaxis (erythromycin ointment is the standard in the US; silver nitrate is no longer recommended)
• Gonococcal ophthalmia neonatorum requires systemic ceftriaxone

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5. Diagnosis and Investigations

• Primary diagnosis is clinical in most cases
• Conjunctival swab culture and Gram stain: Reserved for severe, hyperacute, or neonatal cases; grow on blood agar and chocolate agar
• Fluorescein staining with cobalt blue light: mandatory to rule out corneal involvement - especially important in infants and when viral etiology is suspected
• PCR: Most sensitive test for adenovirus, HSV, chlamydia - used when diagnosis is uncertain or for contact tracing in outbreaks
• Antigen detection tests: Rapid adenovirus assays are available but have variable sensitivity

• Textbook of Family Medicine, 9e

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6. Treatment

6.1 Viral Conjunctivitis

• Largely self-limiting (1-3 weeks)
• Cool compresses
• Artificial tears 5-6 times daily
• Ocular decongestants (e.g., Naphcon-A) 3 times daily as needed
• Antihistamines if itching is prominent
• Antibiotics are NOT indicated (unless bacterial superinfection or etiology is unclear)
• Strict infection control: frequent handwashing, separate towels, no sharing of eye makeup
• HSV keratoconjunctivitis: topical trifluridine or ganciclovir gel; systemic acyclovir for primary or severe disease

6.2 Bacterial Conjunctivitis

• Trimethoprim-polymyxin B - very effective; avoids sulfa and neomycin allergy concerns
• Erythromycin or bacitracin ointment - for mild cases, especially in children
• Topical fluoroquinolone (besifloxacin, gatifloxacin, levofloxacin, moxifloxacin, ofloxacin) - first-line for contact lens wearers (covers Pseudomonas) and for severe cases pending culture results
• Tobramycin - for gram-negative organisms

• Gonococcal: ceftriaxone IM/IV
• Chlamydial: oral azithromycin (1g single dose) or doxycycline (100mg BD x 7 days)

6.3 Allergic Conjunctivitis

• Mild: Artificial tears alone; cool compresses 4 times daily; allergen avoidance
• Moderate: Topical antihistamine/decongestant (e.g., olopatadine, ketotifen); mast cell stabilizers (cromolyn sodium, lodoxamide); or topical NSAIDs
• Severe: Topical corticosteroids (consult ophthalmologist first - risk of activating latent HSV, inducing glaucoma, or cataract with prolonged use)
• Systemic antihistamines for associated rhinitis

6.4 Contact Lens Wearers

• Must be treated with a fluoroquinolone or tobramycin to cover Pseudomonas aeruginosa
• Contact lens wear should be discontinued until infection resolves
• Giant papillary conjunctivitis: switch to preservative-free solutions or daily-wear disposable lenses

• Tintinalli's Emergency Medicine

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7. Complications

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8. Differential Diagnosis of the Red Eye

• Goldman-Cecil Medicine, Tintinalli's Emergency Medicine

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9. Conjunctivitis in Special Contexts

9.1 Contact Lens Wearers

9.2 Immunocompromised Patients

9.3 HIV-Associated Conjunctivitis

9.4 Stevens-Johnson Syndrome (SJS/TEN)

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10. Prevention and Public Health

• Ophthalmia neonatorum prophylaxis: Erythromycin 0.5% ophthalmic ointment at birth (prevents gonococcal and partially chlamydial disease)
• Trachoma - WHO SAFE strategy:
  • Surgery for trichiasis
  • Antibiotics for active infection (oral azithromycin mass drug administration)
  • Facial cleanliness
  • Environmental improvement (access to water and sanitation)
• Contact precautions for EKC: Potentially requires exclusion from work/school; highly contagious via fomites; persists on surfaces for days
• Hand hygiene is the single most effective measure for preventing spread of viral and bacterial conjunctivitis

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11. Summary Comparison Table

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• Tintinalli's Emergency Medicine: A Comprehensive Study Guide
• Robbins & Kumar Basic Pathology
• Tietz Textbook of Laboratory Medicine, 7th Edition
• Bailey and Love's Short Practice of Surgery, 28th Edition
• Textbook of Family Medicine, 9th Edition
• Goldman-Cecil Medicine, International Edition
• Wills Eye Manual - Office and Emergency Room Diagnosis and Treatment of Eye Disease