What is the best treatment approach for an adult patient with a red eye and no significant past medical history?

Treatment of Red Eye Without Remarkable History

For an adult patient presenting with red eye and no significant past medical history, the first priority is to rapidly identify red flag symptoms that require urgent ophthalmology referral—specifically visual loss, moderate-to-severe pain, corneal opacity, severe purulent discharge, or photophobia—and if absent, proceed with supportive care for presumed viral conjunctivitis or targeted treatment based on clinical features. 1

Immediate Red Flag Assessment

Before initiating any treatment, systematically evaluate for the following critical features that mandate same-day ophthalmology referral or emergency department evaluation 1:

• Visual acuity reduction or vision loss 1, 2
• Moderate to severe ocular pain (not relieved by topical anesthetics) 1, 3
• Corneal involvement (loss of transparency, visible opacity, or fluorescein uptake) 1, 3
• Severe purulent discharge (copious, suggesting gonococcal infection) 1, 2
• Photophobia 1, 4
• History of herpes simplex virus eye disease 1, 2
• Immunocompromised state 1, 2
• Contact lens wear (raises concern for keratitis) 1, 5
• Recent ocular trauma or surgery 3, 6

If any red flag is present, refer immediately to ophthalmology—do not initiate empiric treatment. 1, 3

Clinical Differentiation When Red Flags Are Absent

Viral Conjunctivitis (Most Common)

Viral conjunctivitis typically presents with 2:

• Watery discharge (not purulent) 2
• Follicular reaction on inferior tarsal conjunctiva 2
• Preauricular lymphadenopathy 2
• Often starts unilateral but becomes sequentially bilateral within days 1, 2
• Concurrent upper respiratory infection symptoms 2
• Self-limited course (5-14 days) 2

Treatment approach:

• Do NOT prescribe antibiotics—they provide no benefit and may cause unnecessary toxicity 7, 1, 2
• Supportive care only: Preservative-free artificial tears 4 times daily 1, 2
• Cold compresses for symptomatic relief 1
• Topical antihistamines (e.g., olopatadine) may provide symptomatic relief 2
• Patient education: Highly contagious for 10-14 days; minimize contact with others, practice hand hygiene, avoid sharing towels/pillows 2

Bacterial Conjunctivitis

Bacterial conjunctivitis is characterized by 2:

• Mucopurulent or purulent discharge with matted eyelids 2
• Papillary reaction (not follicular) 2
• Can be unilateral or bilateral 2

Treatment approach:

• Mild cases: Often self-limited and may resolve without treatment, but topical antibiotics shorten duration 7, 2
• Moderate to severe cases: 5-7 day course of broad-spectrum topical antibiotic 7, 1, 2
• No specific antibiotic is superior—choose the most convenient or least expensive option (e.g., erythromycin ointment, polymyxin B/trimethoprim drops, fluoroquinolones) 7, 2
• Gatifloxacin 0.5%: Day 1: one drop every 2 hours while awake (up to 8 times); Days 2-7: one drop 2-4 times daily 8

Allergic Conjunctivitis

Allergic conjunctivitis presents with 2:

• Bilateral presentation 2
• Itching as the predominant and distinguishing symptom 2
• Watery discharge 2
• Seasonal or perennial pattern depending on allergen exposure 2
• Concurrent allergic rhinitis or asthma 2
• No preauricular lymphadenopathy or matted eyelids 2

Treatment approach:

• First-line: Topical antihistamines with mast cell-stabilizing activity (olopatadine or ketotifen, 1 drop twice daily) 1, 2
• Environmental modifications: Sunglasses as barrier to airborne allergens, cold compresses, refrigerated artificial tears, avoid eye rubbing 2
• Oral antihistamines as adjunct (less effective than topical for ocular symptoms) 2
• Refractory cases: Short 1-2 week course of low-potency topical corticosteroid (loteprednol etabonate) with IOP monitoring 1, 2

Non-Infectious Causes (Dry Eye, Blepharitis)

When discharge is absent and environmental/seasonal triggers are not present 1:

• Dry eye: Preservative-free artificial tears, warm compresses 1
• Blepharitis: Warm compresses, lid hygiene 1

Critical Pitfalls to Avoid

• Never use topical corticosteroids without ophthalmology supervision—they can prolong adenoviral infections, worsen HSV infections, cause elevated IOP, and induce cataracts 2
• Do not prescribe antibiotics indiscriminately for viral conjunctivitis—this contributes to resistance and causes unnecessary side effects 7, 1, 2
• Avoid topical vasoconstrictors chronically—rebound hyperemia can occur 2
• Do not miss gonococcal conjunctivitis—requires immediate systemic treatment to prevent corneal perforation 2
• Contact lens wear must be discontinued during any infectious conjunctivitis 2

Follow-Up and Referral Indications

Return for evaluation if: 1, 2

• No improvement after 3-4 days of treatment
• Symptoms persist beyond 2-3 weeks
• Development of any red flag symptoms
• Recurrent episodes
• Conjunctival scarring

Refer to ophthalmology for: 1, 2

• Lack of response to appropriate therapy
• Recurrent episodes
• Corneal involvement
• Conjunctival scarring
• Any red flag features

For patients on topical corticosteroids: Regular IOP monitoring and periodic pupillary dilation are mandatory 1, 2