About This Page
This is a clinician-written, evidence-based summary aligned to the 2026 MLA Content Map. It is intended for medical students and junior doctors preparing for the UKMLA. Always cross-reference with NICE guidance, local protocols, and clinical judgement.
Key points
- ALKALI MORE DANGEROUS than acid — liquefactive necrosis penetrates deeper
- Acid causes coagulative necrosis limiting depth (except hydrofluoric acid)
- IMMEDIATE copious irrigation — do NOT delay for assessment
- Continue until pH neutral (7.0–7.4) — check with litmus in the fornices
- Severity: Roper-Hall classification based on corneal clarity and limbal ischaemia
Overview
Chemical eye injury occurs when a corrosive substance contacts the ocular surface. Alkali substances (sodium hydroxide, ammonia, lime/cement, oven cleaners) cause liquefactive necrosis allowing deep penetration. Acid substances cause coagulative necrosis limiting depth — except hydrofluoric acid which behaves like an alkali. Severity depends on substance, concentration, contact time, and volume. Immediate irrigation is the single most important factor.
Epidemiology
Chemical injuries account for ~10–20% of ocular trauma at emergency departments. Alkali injuries are more common (~65%). Males more frequently affected, particularly occupational. Common agents: cement/lime, oven cleaner, ammonia (all alkali), battery acid (acid).
Clinical Features
Symptoms
Immediate severe eye pain and blepharospasm
Reduced visual acuity
A "white eye" after alkali is paradoxically WORSE — severe limbal ischaemia
Signs
Conjunctival hyperaemia or blanched white conjunctiva (severe)
Corneal epithelial defect on fluorescein staining
Corneal haze or opacification
Limbal ischaemia — perilimbal blanching (more = worse prognosis)
Particulate matter in fornices (cement/lime)
Investigations
First-line
pH testing (litmus)Check AFTER irrigation — continue until 7.0–7.4. Re-check at 30 min
Visual acuityDocument after irrigation
Slit-lamp with fluoresceinAssess corneal clarity, epithelial defect, limbal ischaemia
Second-line
IOPMay be raised in severe injury
Evert upper eyelidRemove retained particles
Specialist
Anterior segment photographyDocument limbal ischaemia for Roper-Hall grading
1
IMMEDIATE irrigation (do NOT delay)
- Begin IMMEDIATELY — before any examination
- Copious saline or water for at least 30 minutes
- Sweep fornices to remove particulate matter
- Check pH — continue until 7.0–7.4
- Re-check pH at 30 minutes (alkali particles can cause secondary rise)
2
After irrigation
- Grade I–II (good prognosis): chloramphenicol, cyclopentolate, topical steroid, ascorbic acid
- Grade III–IV (guarded): intensive steroids, ascorbic acid, doxycycline (anti-collagenase), consider amniotic membrane transplant
3
Long-term (severe)
- Limbal stem cell transplantation
- Corneal transplant once inflammation settled
- Manage: symblepharon, dry eye, glaucoma
Complications
- Corneal scarring: May need keratoplasty
- Limbal stem cell deficiency: Prevents epithelial regeneration
- Symblepharon: Conjunctival adhesions
- Secondary glaucoma
- Corneal perforation: From stromal melting
UKMLA Exam Tips
- 1IRRIGATE FIRST, ask questions later — do NOT delay
- 2ALKALI > ACID in severity (liquefactive vs coagulative necrosis)
- 3A WHITE eye after chemical injury is WORSE — limbal/conjunctival vessels destroyed
- 4Continue irrigation until pH neutral (7.0–7.4)
- 5Always evert eyelids and sweep fornices — retained particles continue releasing alkali
- 6Roper-Hall grade IV: opaque cornea + >50% limbal ischaemia = very poor prognosis
practicetest your knowledge on Chemical Eye InjuryApply what you've learnt with UKMLA-style questions from the iatroX Q-Bank — Ophthalmology and beyond.
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