What is conjunctivitis and how is it treated?

Conjunctivitis: Definition and Treatment

Conjunctivitis is inflammation of the conjunctiva that can be infectious (viral or bacterial), allergic, or noninfectious, with treatment determined by identifying the specific etiology through clinical features rather than empiric broad-spectrum therapy. 1

What is Conjunctivitis?

Conjunctivitis is inflammation primarily affecting the conjunctiva—the mucosal membrane covering the anterior sclera and inner eyelid. 1 The condition encompasses a diverse group of diseases affecting all ages worldwide, presenting most commonly with red eye and discharge. 1

Classification by Etiology

Infectious causes:

• Viral conjunctivitis (most common overall cause of infectious conjunctivitis) 2
• Bacterial conjunctivitis (second most common infectious cause) 2

Noninfectious causes:

• Allergic conjunctivitis (affects up to 40% of the population) 2
• Mechanical/irritative/toxic 1
• Immune-mediated 1
• Neoplastic 1

Critical pitfall: Dry eye and blepharitis are the most frequent causes of conjunctival inflammation and must be identified, as treatment should target these underlying problems rather than the conjunctivitis itself. 1

How to Diagnose the Type of Conjunctivitis

Viral Conjunctivitis Features

• Abrupt onset, often unilateral initially but becomes sequentially bilateral 3
• Watery discharge 3, 4
• Follicular reaction on inferior tarsal conjunctiva 3
• Preauricular lymphadenopathy (especially with adenovirus) 3
• Concurrent upper respiratory infection common 3
• May have subconjunctival hemorrhages, chemosis, eyelid swelling 3
• Self-limited, typically resolving in 5-14 days 3

Bacterial Conjunctivitis Features

• Mucopurulent or purulent discharge 3
• Matted eyelids on waking (strongest predictor) 2
• Papillary rather than follicular reaction 3
• Lack of itching 2
• No history of previous conjunctivitis 2
• May have concurrent otitis media, sinusitis, or pharyngitis in children 3
• Preauricular lymphadenopathy less common (unless hypervirulent organisms) 3

Allergic Conjunctivitis Features

• Itching is the most consistent and distinguishing feature 3, 2
• Bilateral presentation 3
• Watery discharge with mild mucous component 5
• History of atopy, asthma, or eczema 5
• Seasonal or perennial pattern depending on allergen 3
• No preauricular lymphadenopathy 3
• No matted eyelids 3

Treatment by Etiology

Viral Conjunctivitis Management

Most cases require supportive care only—antibiotics provide no benefit and should be avoided. 3, 5

Supportive measures:

• Artificial tears for symptomatic relief 3
• Cold compresses 3, 4
• Topical antihistamines for symptomatic relief 3

Patient education critical:

• Highly contagious for 10-14 days from symptom onset 3
• Strict hand hygiene with soap and water 3, 4
• Avoid sharing towels, pillows, or personal items 5
• Disinfect surfaces with EPA-registered hospital disinfectant or 1:10 bleach solution 5

Severe cases with pseudomembranes or marked chemosis:

• Consider short course of topical corticosteroids (1-2 weeks) 3, 5
• Critical warning: Requires close ophthalmology follow-up for monitoring intraocular pressure and periodic pupillary dilation 3, 5
• Can prolong viral shedding and worsen HSV infections 3

Follow-up: Re-evaluate within 1 week if severe; return if symptoms persist beyond 2-3 weeks 3

Bacterial Conjunctivitis Management

Mild cases are self-limited and may resolve without antibiotics, but topical antibiotics can shorten disease duration. 3, 2

For moderate to severe cases:

• 5-7 day course of broad-spectrum topical antibiotic 3
• No specific antibiotic is superior—choose most convenient or least expensive option 3, 5
• Options include: erythromycin ointment, polymyxin B/trimethoprim drops, or fluoroquinolones 3
• Moxifloxacin 0.5%: one drop three times daily for 7 days 6

Return for evaluation if no improvement after 3-4 days of treatment. 5

Special bacterial pathogens requiring systemic therapy:

Gonococcal conjunctivitis:

• Presents with marked eyelid edema, bulbar injection, purulent discharge 3
• Requires systemic antibiotics PLUS topical therapy 3, 5
• Hospitalization necessary for parenteral therapy 5
• Daily follow-up until resolution 5
• Can cause corneal perforation—this is an emergency 3
• Treat sexual contacts concurrently 5

Chlamydial conjunctivitis:

• Requires systemic antibiotic therapy (topical alone is inadequate) 3, 5
• More than 50% of infants have infection at other sites 5
• Treat sexual contacts concurrently 5
• In low-resource settings: povidone-iodine 1.25% ophthalmic solution can be used 5
• Confirm with PCR or immunofluorescent antibody testing 3

Allergic Conjunctivitis Management

First-line treatment: topical antihistamines with mast cell-stabilizing activity 3, 5

• Options include olopatadine or ketotifen 3, 5

Environmental modifications:

• Wear sunglasses as barrier to airborne allergens 3, 5
• Cold compresses 3, 5
• Refrigerated artificial tears 3
• Avoid eye rubbing 3

Persistent or recurrent cases:

• Mast cell stabilizers for maintenance 5

Severe cases:

• Brief course (1-2 weeks) of topical corticosteroids with low side-effect profile 3, 5
• Requires monitoring for intraocular pressure elevation 3

Long-term management:

• Allergen-specific immunotherapy beneficial, especially in children 3
• Multidisciplinary approach with allergists recommended 3

Red Flags Requiring IMMEDIATE Ophthalmology Referral

Refer urgently if ANY of the following are present: 3, 5

• Visual loss or decreased vision 3, 5
• Moderate or severe pain 3, 5
• Severe purulent discharge 3, 5
• Corneal involvement (fluorescein staining shows epithelial defects) 3, 5
• Conjunctival scarring 3, 5
• Lack of response to therapy 3, 5
• Recurrent episodes 3, 5
• History of HSV eye disease 3, 5
• Immunocompromised state 3, 5
• Recent ocular surgery 5, 4
• Vesicular rash on eyelids or nose 4
• Neonatal conjunctivitis (requires prompt evaluation, may need hospitalization) 3

Critical Pitfalls to Avoid

Do not prescribe antibiotics indiscriminately for viral conjunctivitis—they provide no benefit, cause unnecessary toxicity, and contribute to antibiotic resistance. 3, 5

Do not use topical corticosteroids without ophthalmology supervision—they can prolong adenoviral infections, worsen HSV infections, cause elevated intraocular pressure, and promote cataract formation. 3, 5

Do not allow contact lens wear during any infectious conjunctivitis—suspend use until complete resolution. 3, 5

Do not miss gonococcal conjunctivitis—it can cause corneal perforation and requires immediate systemic treatment. 3

Do not fail to consider child abuse—sexually transmitted conjunctivitis in children mandates evaluation for abuse and appropriate reporting. 3

Do not overlook chronic/recalcitrant conjunctivitis—may indicate underlying malignancy such as sebaceous or squamous cell carcinoma. 3

Contact Lens-Related Conjunctivitis

• Ranges from mild injection to severe corneal scarring 1
• Caused by mechanical irritation, chronic hypoxia, or preservatives 1
• Subacute to acute onset; may take months to resolve even with treatment and lens withdrawal 1
• Suspend contact lens wear immediately 3, 5
• Appropriate lens care and frequent replacement reduces risk 3

Prevention Strategies

For infectious conjunctivitis: 3, 5

• Hand hygiene with soap and water (single most important measure) 5
• Avoid sharing towels, pillows, cosmetics 5
• Disinfect surfaces with EPA-registered disinfectant or 1:10 bleach solution 5
• Minimize contact with others for 10-14 days if viral 3

For allergic conjunctivitis: 3

• Allergen avoidance 3
• Consider immunotherapy for severe cases 3

Herpes zoster vaccination strongly recommended in patients 50 years or older. 1