What is the recommended treatment for a patient presenting with conjunctivitis, considering potential bacterial, allergic, or viral causes?

Treatment of Conjunctivitis

For uncomplicated bacterial conjunctivitis in immunocompetent patients, initiate moxifloxacin 0.5% three times daily for 5-7 days as the preferred first-line topical antibiotic, while viral conjunctivitis requires only supportive care with cold compresses and artificial tears, and allergic conjunctivitis responds best to topical antihistamines with mast cell-stabilizing activity such as olopatadine or ketotifen. 1

Initial Clinical Assessment

The diagnosis hinges on identifying specific clinical features that distinguish between etiologies:

Bacterial Conjunctivitis Features

• Mucopurulent or purulent discharge with matted eyelids upon waking 2, 3
• Papillary reaction on tarsal conjunctiva (not follicular) 2
• Unilateral or bilateral presentation 2
• Absence of itching and preauricular lymphadenopathy (unless hypervirulent organisms) 2, 4

Viral Conjunctivitis Features

• Watery discharge with follicular reaction on inferior tarsal conjunctiva 2, 3
• Preauricular lymphadenopathy commonly present 2
• Often starts unilateral but becomes sequentially bilateral 2
• May have concurrent upper respiratory infection 2
• Subconjunctival hemorrhages and chemosis may be present 2

Allergic Conjunctivitis Features

• Itching is the most consistent and distinguishing feature 2, 4
• Bilateral presentation with watery discharge 2
• Absence of preauricular lymphadenopathy and matted eyelids 2
• Often seasonal or perennial pattern with concurrent allergic rhinitis 2

Treatment Algorithm by Etiology

Bacterial Conjunctivitis

Mild to Moderate Cases:

• Initiate moxifloxacin 0.5% three times daily for 5-7 days as first-line therapy due to superior efficacy and faster symptom resolution 1
• Fourth-generation fluoroquinolones (moxifloxacin, gatifloxacin) provide superior gram-positive coverage including some methicillin-resistant S. aureus strains 5
• For uncomplicated mild cases, any broad-spectrum topical antibiotic may be selected based on convenience or cost, as no single agent shows superiority 5, 2
• Erythromycin ophthalmic ointment approximately 1 cm in length applied up to six times daily is an alternative option 6
• Instruct patients to return in 3-4 days if no improvement occurs 1, 5

Contact Lens Wearers:

• Require fluoroquinolones due to higher risk of Pseudomonas infection 5
• Contact lens wear must be discontinued during any infectious conjunctivitis 2

MRSA Suspected Cases:

• May require compounded topical vancomycin, as MRSA isolates are generally resistant to fluoroquinolones and aminoglycosides 5

Gonococcal Conjunctivitis (Vision-Threatening Emergency)

Critical action required immediately:

• Obtain conjunctival cultures and Gram staining before treatment 5
• Ceftriaxone 1 g IM single dose PLUS azithromycin 1 g orally single dose for adults 1
• Weight-based ceftriaxone dosing for children 1
• Add topical therapy and saline lavage for comfort 5
• Hospitalization necessary for parenteral therapy with daily follow-up until resolution 2
• Treat sexual contacts 2

Chlamydial Conjunctivitis

Systemic therapy is mandatory (topical treatment alone is insufficient):

• Azithromycin 1 g orally single dose is preferred 1
• Alternative: doxycycline 100 mg orally twice daily for 7 days 1
• For neonates: erythromycin base or ethylsuccinate 50 mg/kg/day divided into four doses daily for 14 days 5
• Evaluate and treat sexual partners 2
• Re-evaluate after treatment completion 2

Viral Conjunctivitis

Supportive care only (antibiotics provide no benefit and may cause toxicity):

• Cold compresses and preservative-free artificial tears for symptomatic relief 1, 2
• Topical antihistamines may provide additional symptomatic relief 2
• Avoid topical antibiotics entirely 2
• Self-limited course, typically resolving within 5-14 days 2

Patient education is critical:

• Highly contagious for 10-14 days from symptom onset 2
• Wash hands frequently with soap and water (not sanitizer alone) 7
• Use separate towels and pillows 7
• Avoid touching eyes and close contact with others 7

Severe cases with marked chemosis or pseudomembranes:

• Consider short course of topical corticosteroids only with close ophthalmology follow-up 2
• Monitor intraocular pressure regularly and perform periodic pupillary dilation 2
• Caution: Corticosteroids may prolong viral shedding and worsen HSV infections 2

Allergic Conjunctivitis

First-line treatment:

• Topical antihistamines with mast cell-stabilizing activity (olopatadine or ketotifen) 1, 2
• Environmental modifications: wear sunglasses, use cold compresses, refrigerated artificial tears 2
• Avoid eye rubbing 2

Refractory cases:

• Brief 1-2 week course of topical corticosteroids with low side-effect profile 2
• Allergen-specific immunotherapy (subcutaneous or sublingual) is beneficial, especially in children 7

Critical Red Flags Requiring Immediate Ophthalmology Referral

Refer urgently for any of the following: 1, 5, 2

• Visual loss or decreased vision
• Moderate to severe pain
• Severe purulent discharge
• Corneal involvement (infiltrates, ulcers, opacification)
• Conjunctival scarring
• Lack of response after 3-4 days of appropriate therapy
• History of herpes simplex virus eye disease
• Immunocompromised state
• Neonatal conjunctivitis
• Recurrent episodes

Common Pitfalls and How to Avoid Them

Avoid indiscriminate antibiotic use:

• Viral conjunctivitis accounts for unnecessary antibiotic prescriptions, promoting resistance 5
• Delayed antibiotic prescribing for bacterial conjunctivitis has similar symptom control as immediate prescribing 3

Never use topical corticosteroids without ophthalmology supervision:

• Can prolong adenoviral infections and worsen HSV infections 2
• Risk of elevated intraocular pressure and cataract formation 2
• Should never be used unless conjunctivitis is proven nonherpetic 8

Do not miss sexually transmitted infections:

• Gonococcal conjunctivitis can cause corneal perforation if untreated 2
• Both gonococcal and chlamydial conjunctivitis require systemic therapy plus evaluation of sexual partners 1, 2
• Consider sexual abuse in children presenting with these infections 5

Recognize chronic/recalcitrant cases:

• May indicate underlying malignancy (sebaceous or squamous cell carcinoma) requiring further evaluation 2

Infection control measures are essential:

• Hand hygiene with soap and water is the most effective prevention measure 7, 1
• Patients should avoid sharing towels, pillows, and personal items 7
• Healthcare workers and childcare providers should avoid work during contagious period 7