What are the red flag signs and potential underlying conditions to consider in a patient presenting with red eyes, particularly in those with a history of trauma, recent travel, autoimmune disorders, cancer, or recent eye surgery?

Red Eye Red Flag Signs

Any patient presenting with red eyes who has visual acuity loss, moderate-to-severe eye pain, significant photophobia, corneal damage, or pupillary abnormalities requires emergency ophthalmology evaluation within 24 hours, as these signs indicate potentially vision-threatening or life-threatening conditions. 1, 2, 3

Critical Red Flag Signs Requiring Emergency Referral (<24 Hours)

Vision-Threatening Symptoms

• Visual acuity loss or significant blurred vision - indicates potential keratitis, uveitis, acute angle-closure glaucoma, or retinal artery occlusion 1, 2, 3
• Moderate to severe eye pain (beyond irritation or foreign body sensation) - suggests corneal ulceration, infectious keratitis, acute angle-closure glaucoma, scleritis, or anterior uveitis 1, 2, 4, 3
• Severe photophobia - indicates corneal involvement, anterior uveitis/iritis, or keratitis 1, 2, 3

Examination Findings

• Corneal damage - visible fluorescein uptake, corneal opacity, haze, ulceration, or epithelial defects indicate infectious keratitis or corneal perforation risk 1, 2
• Mid-dilated or poorly reactive pupil - suggests acute angle-closure glaucoma, anterior uveitis, or traumatic injury 2
• Loss of corneal transparency and specular reflex - indicates corneal edema from acute glaucoma or severe keratitis 5
• Copious purulent discharge - particularly with marked eyelid edema suggests gonococcal conjunctivitis with risk of corneal perforation 1, 4

High-Risk Presentations

• Unilateral redness with any other red flag - more concerning than bilateral presentation, suggests focal pathology including infection, trauma, or vascular occlusion 1, 6
• Eyelid swelling with pain, proptosis, or restricted eye movements - indicates preseptal or orbital cellulitis 2
• Redness with recent eye surgery - risk of endophthalmitis or wound dehiscence 1, 4

Special Population Considerations

Recent Trauma History

• Any penetrating or blunt ocular injury - increased risk of retinal detachment, globe rupture, or intraocular foreign body 1
• Chemical exposure - requires immediate copious irrigation and urgent ophthalmology consultation 1, 4
• Post-traumatic symptoms (flashes, floaters, curtain-like vision loss) - 8-22% risk of retinal tear with acute posterior vitreous detachment 1

Recent Travel

• Exposure to infected individuals - consider gonococcal or chlamydial conjunctivitis, particularly with purulent discharge 1
• Travel to areas with poor sanitation - evaluate for trachoma (Chlamydia trachomatis serotypes A, B, C) if follicular conjunctivitis with corneal pannus present 1

Autoimmune Disorders

• Patients with known rosacea, atopic dermatitis, psoriasis, or graft-versus-host disease - higher risk of chronic blepharitis and severe ocular surface disease 1
• Chronic red eyes refractory to topical therapy - may indicate carotid cavernous fistula, vasculitis, or systemic inflammatory disease requiring systemic workup 7
• Bilateral disc edema with diffuse chorioretinal changes - consider Vogt-Koyanagi-Harada disease, sarcoidosis, or multifocal choroiditis requiring immediate high-dose corticosteroids (1 mg/kg/day prednisolone) 8

Cancer Patients

• Immunosuppressed patients with red eye - higher risk of opportunistic infections including herpes simplex keratitis, fungal keratitis, or cytomegalovirus retinitis 7
• Misdiagnosis risk - immune-related conditions may be incorrectly attributed to cancer treatment when infectious or compressive etiologies exist 7

Recent Eye Surgery

• Post-cataract surgery patients - 1% risk of retinal detachment, higher in myopic patients or those with vitreous loss during surgery 1
• Symptoms occurring 1-2 years post-surgery - peak time for retinal detachment due to postoperative posterior vitreous detachment 1
• Post-refractive surgery - evaluate for infectious keratitis, particularly if epithelial defect present 4

Algorithmic Approach to Red Eye Assessment

Step 1: Immediate Triage Using RAPID Acronym 1

• Redness (unilateral more concerning than bilateral)
• Acuity loss
• Pain (moderate-severe, not just irritation)
• Intolerance to light (photophobia)
• Damage to cornea

If ANY component beyond redness alone is present → Emergency ophthalmology referral <24 hours 1, 2

Step 2: Risk Stratification for Patients Without Red Flags

Mild Presentation 1, 6

• Bilateral mild redness without pain, normal vision, no photophobia
• Management: Preservative-free lubricants 2-4 times daily, warm compresses, lid hygiene 1, 6
• Follow-up: Reassess in 2-4 weeks; refer if no improvement 6

Moderate Presentation 1, 6

• Bilateral moderate redness with mild irritation but normal vision
• Management: Preservative-free lubricants 2-4 times daily PLUS topical antihistamine (olopatadine) twice daily 1, 6
• Follow-up: Ophthalmology within 4 weeks if requiring escalation 1

Severe Presentation 1

• Bilateral severe redness without other red flags
• Management: Preservative-free lubricants 2-4 times daily PLUS tacrolimus 0.1% ointment once daily to lid margins 1
• Referral: Ophthalmology assessment within 4 weeks 1

Step 3: Special Pediatric Considerations

• Children <7 years with ANY ocular symptoms - refer to ophthalmology within 4 weeks due to visual development plasticity 1
• Neonates with purulent discharge - consider gonococcal (manifests 1-7 days after birth) or chlamydial conjunctivitis (5-19 days after birth); both require immediate treatment to prevent corneal perforation and systemic complications 1

Common Pitfalls to Avoid

• Do not delay ophthalmology referral while awaiting diagnostic workup if inflammatory choroiditis or severe infection is suspected - visual outcomes depend on immediate intervention 8
• Do not initiate topical corticosteroids empirically in red eye with corneal involvement - may worsen infectious keratitis or mask severity 2, 4
• Do not assume bilateral presentation is benign - bilateral disc edema with red eyes may indicate life-threatening conditions like giant cell arteritis or severe systemic inflammation 1, 8
• Do not attribute all red eyes in immunosuppressed patients to immune-related disease - infectious etiologies are more common and require different management 7
• Do not confuse dupilumab-related ocular surface disease with infectious conjunctivitis - bilateral presentation is typical for drug-related causes, while unilateral suggests alternative etiology 1, 6

Conditions Requiring Systemic Workup

Retinal/Ophthalmic Artery Occlusion 1

• Stroke risk up to 25% with newly diagnosed arterial occlusion
• Immediate transfer to stroke center for acute nonarteritic cases
• Evaluate for giant cell arteritis in patients ≥50 years (ESR, CRP, temporal artery biopsy)
• Assess for embolic sources, carotid dissection, antiphospholipid antibodies

Inflammatory Choroiditis with Disc Edema 8

• Start high-dose oral prednisolone 1 mg/kg/day (maximum 60 mg/day) immediately without waiting for complete workup
• Add steroid-sparing immunosuppression (mycophenolate mofetil preferred) within 4-8 weeks
• Obtain OCT, fluorescein angiography, indocyanine green angiography to characterize disease