What is the appropriate evaluation and management of a patient presenting with red eye?

Red Eye Evaluation and Management

Immediate Red Flag Assessment

Any patient presenting with red eye accompanied by pain, vision loss, corneal opacity, severe purulent discharge, or photophobia requires same-day ophthalmology referral or emergency department evaluation. 1

Critical red flags demanding urgent ophthalmology consultation within 24 hours include:

• Visual loss or decreased visual acuity 1, 2
• Moderate to severe ocular pain (especially if not relieved by topical anesthetics) 1, 2
• Corneal involvement (loss of transparency, opacity, or visible damage) 1, 2
• Severe purulent discharge, particularly if unilateral 1, 2
• History of herpes simplex virus eye disease 1, 2
• Immunocompromised status 1, 2
• Recent ocular surgery or trauma 2

Initial Clinical Evaluation

Key History Elements to Obtain

• Duration and onset of symptoms (abrupt vs gradual) 3
• Unilateral vs bilateral presentation (unilateral suggests more serious pathology including HSV, bacterial infection, or corneal disease) 1, 2
• Character of discharge (watery, purulent, mucopurulent, or absent) 1, 3
• Contact lens wear history including type, overnight wear, tap water exposure, and hygiene practices 3
• Associated symptoms: itching (suggests allergy), pain severity, photophobia, foreign body sensation 3
• Concurrent upper respiratory infection (suggests viral conjunctivitis) 3
• History of atopy, asthma, or eczema (suggests allergic conjunctivitis) 2, 3
• Sexual activity and risk factors (gonococcal or chlamydial conjunctivitis) 3

Essential Physical Examination Components

• Visual acuity testing using eye chart (with corrective lenses if worn) 4
• Pupillary examination including size, shape, symmetry, and swinging-light test for afferent pupillary defect 4
• Red reflex examination to detect corneal opacities or media abnormalities 4
• External inspection for eyelid swelling, erythema, vesicular lesions, or proptosis 4
• Penlight examination of anterior eye to assess corneal clarity and transparency 4, 3
• Conjunctival assessment for follicles (viral) vs papillae (bacterial/allergic), chemosis, and hemorrhage 3
• Preauricular lymphadenopathy (suggests viral or gonococcal infection) 3

Differential Diagnosis Based on Clinical Presentation

Viral Conjunctivitis

Clinical features:

• Watery discharge with follicular reaction on inferior tarsal conjunctiva 2, 3
• Abrupt onset, often unilateral initially but becomes sequentially bilateral within days 1, 3
• Preauricular lymphadenopathy commonly present 2, 3
• Concurrent upper respiratory infection frequently associated 3
• Subconjunctival hemorrhages and chemosis may be present 3
• Self-limited course resolving within 5-14 days 2

Bacterial Conjunctivitis

Clinical features:

• Purulent or mucopurulent discharge with matted eyelids 2, 3
• Papillary reaction rather than follicular 2, 3
• Unilateral or bilateral presentation 3
• May be associated with otitis media, sinusitis, or pharyngitis in children 2, 3

Gonococcal Conjunctivitis (Sight-Threatening Emergency)

Clinical features:

• Marked eyelid edema with severe bulbar conjunctival injection 2, 3
• Copious purulent discharge 2, 3
• Rapid progression to corneal infiltrate, ulcer, and potential perforation 2, 3
• Requires immediate systemic treatment in addition to topical therapy 1, 3

Allergic Conjunctivitis

Clinical features:

• Itching as the predominant and distinguishing symptom 2, 3
• Bilateral presentation with watery discharge and mild mucous component 2
• Seasonal or perennial pattern depending on allergen exposure 2
• History of atopy, asthma, or eczema 2, 3
• Absence of preauricular lymphadenopathy 3

Herpes Simplex Virus Conjunctivitis

Clinical features:

• Usually unilateral (bilateral in atopic, pediatric, or immunocompromised patients) 3
• Vesicular rash or ulceration of eyelids 3
• Dendritic epithelial keratitis on corneal examination 3
• Requires immediate ophthalmology referral 1, 2

Management Algorithm by Etiology

Viral Conjunctivitis Management

The American Academy of Ophthalmology recommends that viral conjunctivitis does not respond to antibacterial agents and should not be treated with antibiotics. 1, 3

• Supportive care with preservative-free artificial tears 4 times daily 1
• Cold compresses for symptomatic relief 1
• Topical antihistamines may provide additional symptomatic relief 3
• Patient education about high contagiousness: minimize contact with others for 10-14 days from symptom onset 3
• Strict hand hygiene with soap and water to prevent transmission 3
• Avoid sharing personal items (towels, pillows) and disinfect surfaces 3

For severe cases with marked chemosis and lid swelling:

• Short course of topical corticosteroids may be considered, but requires close ophthalmology follow-up 3
• Regular monitoring of intraocular pressure and periodic pupillary dilation mandatory 1, 3
• Caution: corticosteroids may prolong viral shedding and worsen HSV infections 3

Bacterial Conjunctivitis Management

For mild bacterial conjunctivitis:

• Often self-limited and may resolve without treatment 3
• Topical antibiotics may decrease duration of infection 3

For moderate to severe bacterial conjunctivitis:

• 5-7 day course of broad-spectrum topical antibiotic 1, 3
• No specific antibiotic is superior: choose most convenient or least expensive option 3
• Options include erythromycin ointment, polymyxin B/trimethoprim drops, or fluoroquinolones 3

Critical pitfall: Do not prescribe antibiotics indiscriminately for presumed bacterial conjunctivitis when viral etiology is more likely, as this contributes to resistance and unnecessary toxicity 3

Gonococcal Conjunctivitis Management (Emergency)

• Systemic antibiotic therapy mandatory in addition to topical treatment 1, 3
• Hospitalization necessary for parenteral therapy 3
• Daily follow-up required until resolution 3
• Treatment of sexual contacts essential 3
• Conjunctival scrapings for Gram stain and culture before initiating antibiotics 3

Chlamydial Conjunctivitis Management

• Systemic treatment required (topical therapy alone inadequate) 1, 3
• Evaluation and treatment of sexual partners mandatory 1, 3
• PCR or immunofluorescent antibody testing for confirmation 3

Allergic Conjunctivitis Management

First-line treatment:

• Topical antihistamines with mast cell-stabilizing activity (olopatadine or ketotifen) 1 drop twice daily 1, 3
• Environmental modifications: wear sunglasses as barrier to airborne allergens 3
• Cold compresses and refrigerated artificial tears 3
• Avoid eye rubbing 3

For refractory cases:

• Short 1-2 week course of low-potency topical corticosteroid (loteprednol etabonate) 1
• Baseline and periodic IOP monitoring required 1
• Allergen-specific immunotherapy beneficial, especially in children 3

When Laboratory Testing Is Indicated

Routine bacterial conjunctivitis does not require cultures in otherwise healthy patients 3

Mandatory microbiologic testing situations:

• Neonatal conjunctivitis (any suspected infectious etiology) 3
• Suspected gonococcal conjunctivitis (any age) 3
• Recurrent, severe, or chronic purulent conjunctivitis 3
• Failure to improve after 5-7 days of topical antibiotics 3
• Sexually active individuals with heightened risk of Neisseria gonorrhoeae 3

Technique: Obtain conjunctival scrapings for Gram and Giemsa stains plus cultures before initiating antibiotic therapy to avoid false-negative results 3

Mandatory Ophthalmology Referral Criteria

Refer urgently (same day or within 24 hours) for:

• Visual loss or decreased vision 1, 2
• Moderate to severe pain not relieved by topical anesthetics 1, 2
• Corneal involvement (opacity, loss of transparency) 1, 2
• Severe purulent discharge 1, 2
• History of herpes simplex virus eye disease 1, 2
• Immunocompromised status 1, 2
• Recent ocular surgery or trauma 2

Refer within a few days for:

• Lack of response to therapy after 3-4 days 1
• Recurrent episodes 1, 3
• Conjunctival scarring 1, 3
• Any diagnostic uncertainty 5, 6

Common Pitfalls to Avoid

• Never prescribe antibiotics for viral conjunctivitis: they provide no benefit and cause unnecessary toxicity and resistance 1, 3
• Do not miss gonococcal conjunctivitis: requires immediate systemic treatment to prevent corneal perforation 2, 3
• Avoid topical corticosteroids without ophthalmology supervision: can cause elevated IOP, cataracts, and worsen HSV infections 2, 3
• Do not start corticosteroids before eye exam unless systemic steroids indicated for non-ophthalmological toxicity, as may worsen herpetic infections or mask accurate diagnosis 4
• Recognize that unilateral red eye requires broader differential: consider HSV, bacterial infection, corneal pathology, anterior uveitis, or acute angle-closure glaucoma 1, 2
• Contact lens wear must be discontinued during any infectious conjunctivitis 3

Follow-Up Recommendations

• Severe viral conjunctivitis: re-evaluate within 1 week 3
• Uncomplicated cases not on corticosteroids: return if symptoms persist beyond 2-3 weeks 3
• Patients on topical corticosteroids: regular IOP monitoring and periodic pupillary dilation 1, 3
• Bacterial conjunctivitis: return if no improvement after 5-7 days of antibiotics 3