Corneal ulcer/abrasion

Overview

•Corneal abrasion - superficial mechanical disruption of corneal epithelium (trauma)

•Corneal ulcer (microbial keratitis) - active infection of corneal stroma by bacteria, fungi, protozoa, or viruses

Presentation

•Painful red eye - severe, disproportionate to visible injury

•Photophobia, foreign body sensation, epiphora (excessive tearing)

•Reduced visual acuity - suggests central or stromal involvement

•Corneal infiltrate/white opacity - distinguishes ulcer from simple abrasion

Investigations

🥇 First-line

•Fluorescein staining with cobalt blue light - epithelial defects fluoresce bright green; dendritic pattern = herpes simplex keratitis

•Visual acuity (Snellen chart) - quantifies severity

•Slit-lamp examination - identifies stromal infiltrates, anterior chamber reaction

🏆 Gold standard

•Corneal scraping with culture and sensitivity - for suspected microbial keratitis, guides targeted therapy

⚠️

Topical anaesthetic (e.g. tetracaine) can be used to facilitate examination but must NOT be prescribed for take-home use - it impairs corneal epithelial healing and masks symptoms.

Management

•First-line (corneal abrasion): chloramphenicol eye drops or ointment - ointment four times daily for 7 days (also lubricates)

•Second-line / alternative: fusidic acid eye drops twice daily - use in pregnancy, children, elderly, or personal/family history of blood dyscrasias (aplastic anaemia risk with chloramphenicol)

•Contact lens wearers (first-line): ciprofloxacin or ofloxacin eye drops - antipseudomonal cover essential

•Analgesia - oral paracetamol or NSAIDs; topical NSAIDs (e.g. ketorolac) have Cochrane evidence for pain relief

•Eye patching - NOT recommended; occlusion impairs blinking (needed for re-epithelialisation) and encourages bacterial growth

•Contact lenses - avoid until cornea fully healed and at least 24 hours after completing antibiotics

•Corneal ulcer - urgent same-day ophthalmology referral; intensive topical antibiotics + corneal scraping for culture

🚨

Refer urgently to ophthalmology: contact lens wearer with any epithelial defect, corneal infiltrate/white opacity, significant reduced VA, symptoms worsening after 48-72 hours, suspected penetrating injury, or only-seeing eye.

Risk factors for corneal ulcer

•Steroid eye drops - suppress local immune surveillance (neutrophil/macrophage activity), allowing opportunistic organisms to proliferate unchecked

•Contact lens wear (especially overnight/extended wear) - hypoxic environment favours Pseudomonas aeruginosa

•Corneal trauma, immune suppression

🎯

Steroid eye drops are a classic cause of corneal ulcer - they reduce corneal immune defence, enabling bacterial, fungal, or protozoal infection. Saline, lubricant, antibacterial, and antifungal drops are not causative.