What is the appropriate next step for a 61‑year‑old man with sudden unilateral red sclera, eye pain and photophobia that worsens with eye drops?

Urgent Ophthalmology Referral Within 24 Hours

This patient requires same-day ophthalmology evaluation—the combination of acute unilateral red eye, pain, photophobia, and worsening symptoms with eye drops represents a vision-threatening emergency until proven otherwise. 1, 2

Why This Cannot Wait

The triad of pain, redness, and photophobia indicates serious anterior segment pathology that demands immediate specialist assessment to prevent permanent vision loss. 2 Delaying diagnosis risks irreversible complications including:

• Bacterial keratitis (especially if any history of trauma, contact lens use, or corneal disease) 3
• Herpes zoster ophthalmicus or HSV keratouveitis (can cause rapid stromal destruction and permanent scarring) 1
• Acute angle-closure glaucoma (18% of untreated eyes become blind, 58% have vision worse than 20/40) 2
• Severe anterior uveitis (can progress to vision loss within hours) 2

The fact that eye drops caused stinging is a critical red flag—this suggests either epithelial disruption (corneal pathology) or severe inflammation, neither of which should be managed empirically without slit-lamp examination. 1, 3

Critical Examination Findings Needed Before Treatment

Do not initiate any treatment until ophthalmology performs:

• Slit-lamp biomicroscopy to identify stromal infiltrates, anterior chamber reaction, or corneal edema 3, 2
• Fluorescein staining (mandatory—can reveal corneal involvement not visible on gross examination, including dendritic HSV patterns or epithelial defects) 1, 3
• Intraocular pressure measurement (to rule out acute angle-closure) 2
• Pupil examination (mid-dilated poorly reactive pupil suggests angle-closure; normal pupil doesn't exclude keratitis or uveitis) 2

What You Must Rule Out First

Bacterial Keratitis

• Presents with pain, photophobia, and foreign body sensation mimicking abrasion 3
• Key finding: Suppurative stromal infiltrates >1mm with indistinct edges, surrounding edema, and anterior chamber reaction 3
• Can occur without visible epithelial defect 3
• Risk factors: contact lens wear (especially overnight), recent trauma, previous corneal surgery, dry eye 3

Herpes Zoster Ophthalmicus or HSV Keratouveitis

• Unilateral presentation with eyelid involvement, conjunctival injection, and preauricular lymphadenopathy 1
• Requires immediate systemic antiviral therapy—permanent vision loss occurs rapidly if treatment is delayed 1
• Fluorescein shows dendritic pattern in HSV 1

Acute Angle-Closure Glaucoma

• Blurred vision, severe pain, photophobia with mid-dilated poorly reactive pupil 2
• Requires emergent IOP-lowering treatment within hours 2

Critical Management Pitfalls to Avoid

• Never assume "just conjunctivitis" based on redness alone—the presence of pain and photophobia indicates deeper pathology 2
• Never patch the eye—increases risk of bacterial keratitis progression 3
• Never start topical corticosteroids empirically—can worsen infectious keratitis and HSV, leading to corneal perforation 3
• Never dismiss the stinging from eye drops—this indicates epithelial compromise or severe inflammation requiring specialist evaluation 1, 3
• Never delay antiviral therapy if HSV/VZV is suspected—permanent vision loss can occur within 24-48 hours 1

Immediate Action Plan

While arranging urgent ophthalmology referral:

1. Do not instill any additional eye drops (including lubricants or antibiotics) until after slit-lamp examination 1, 3
2. Avoid eye manipulation or pressure 3
3. Document visual acuity in the affected eye 2
4. Ask specifically about:
   • Contact lens wear (especially overnight) 3
   • Recent eye trauma or foreign body 3
   • Previous corneal surgery or chronic dry eye 3
   • Immunosuppression 3
   • Vesicular rash on forehead/scalp (zoster distribution) 1

If ophthalmology is unavailable within 2-4 hours, send to emergency department for immediate evaluation, as this presentation requires slit-lamp examination and fluorescein staining before any treatment decisions. 2