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This is a clinician-written, evidence-based summary aligned to the USMLE Step 2 CK Content Outline. It is intended for medical students preparing for USMLE Step 2 CK. Management reflects current ACC/AHA, USPSTF, and APA guidelines. Always cross-reference with UpToDate, institutional protocols, and clinical judgment.
The Bottom Line
- Chemical eye injury is a true emergency: irrigation starts immediately before visual acuity, full history, or ophthalmology arrival
- Alkali burns are usually worse than acid burns because they penetrate ocular tissues rapidly by liquefactive necrosis
- Use any available noncaustic fluid initially; continue until ocular pH is physiologic and remains stable
- Remove contact lenses and sweep fornices to remove retained particulate matter
- Severity is determined by corneal haze, epithelial defect size, limbal ischemia, conjunctival involvement, and IOP
Overview
Chemical eye injury occurs when corrosive substances damage the conjunctiva, cornea, limbus, and anterior segment. Alkali injuries, such as ammonia, lye, cement, plaster, drain cleaner, and lime, are especially dangerous because they penetrate rapidly and saponify cell membranes. Acid injuries often coagulate superficial proteins, which may limit penetration, although hydrofluoric acid is an important exception. Immediate dilution and normalization of ocular pH is the single most important intervention.
Epidemiology
Chemical eye injuries occur in occupational, household, agricultural, laboratory, assault, and pediatric settings. Common exposures include cleaning agents, drain cleaners, industrial chemicals, cement/lime, fertilizers, pool chemicals, and battery acid. Severity depends on pH, concentration, exposure duration, penetration, retained particulate matter, and speed of irrigation. Delayed irrigation is the major modifiable determinant of poor outcome.
Clinical Features
Symptoms
Immediate severe eye pain, burning, tearing, blepharospasm, and photophobia
Blurred vision or inability to open eye
History of chemical splash, powder exposure, workplace accident, cleaning product exposure, or assault
Pain may paradoxically be less severe in very severe burns due to corneal nerve damage
Contact lens use may retain chemical against the ocular surface
Signs
Conjunctival injection, chemosis, epithelial sloughing, or blanching
Corneal epithelial defect with fluorescein staining
Corneal haze or opacification indicates more severe injury
Limbal ischemia/blanching predicts stem cell injury and poor prognosis
Elevated IOP can occur from trabecular meshwork damage or inflammation
Retained particulate matter in fornices can continue chemical injury
Investigations
First-line
Immediate ocular pH testingCheck pH when feasible but do not delay irrigation; target physiologic pH around 7.0-7.4 and recheck after irrigation pause
Visual acuityDocument once irrigation is underway or after initial stabilization; do not delay irrigation for acuity testing
Fluorescein stainingAssesses epithelial defect and corneal involvement after pH is stabilized
Second-line
Slit-lamp examinationAssess corneal haze, limbal ischemia, conjunctival necrosis, anterior chamber inflammation, and retained particles
Intraocular pressureMeasure after initial irrigation if globe integrity is intact; elevated IOP worsens prognosis
Eyelid eversion / fornix sweepEssential to remove retained particles such as lime or cement that continue to leach alkali
Specialist
Ophthalmology assessmentUrgent for all but the most trivial exposures; mandatory for corneal defect, abnormal pH, vision change, limbal ischemia, or alkali injury
1
Immediate irrigation — do first
- Start copious irrigation immediately with normal saline, lactated Ringer solution, balanced salt solution, or water if nothing else is available
- Do not delay irrigation for history, visual acuity, consent paperwork, pH strip, or ophthalmology arrival
- Instill topical anesthetic to facilitate eyelid opening and irrigation
- Remove contact lenses immediately
- Evert eyelids and sweep fornices repeatedly to remove particulate matter
- Continue irrigation until ocular pH is physiologic and remains stable after a pause
2
After pH normalization
- Assess visual acuity, pupil, cornea, conjunctiva, limbus, anterior chamber, and IOP
- Topical antibiotic ointment/drop for epithelial defect infection prophylaxis
- Cycloplegic such as cyclopentolate or atropine for pain from ciliary spasm
- Preservative-free artificial tears and lubricating ointment
- Oral analgesia and tetanus update if associated trauma
3
Moderate to severe burns
- Urgent ophthalmology-directed therapy may include topical corticosteroids early, ascorbate, citrate, doxycycline, IOP-lowering agents, bandage contact lens, amniotic membrane, or surgery
- Avoid unsupervised topical anesthetic use after discharge
- Hospitalization may be needed for severe bilateral injury, unreliable irrigation/follow-up, child safeguarding concerns, or vision-threatening burns
4
Follow-up
- Daily ophthalmology follow-up initially for significant epithelial defects, limbal ischemia, corneal haze, or IOP elevation
- Monitor for delayed complications: symblepharon, limbal stem cell deficiency, glaucoma, dry eye, corneal melt, and scarring
Complications
- Corneal scarring/opacification: Can cause permanent visual impairment
- Limbal stem cell deficiency: Conjunctivalization, recurrent epithelial breakdown, and chronic vision loss
- Corneal melt/perforation: Severe inflammatory stromal degradation
- Secondary glaucoma: Trabecular meshwork injury and inflammation can raise IOP
- Symblepharon: Adhesions between palpebral and bulbar conjunctiva
- Severe dry eye: Goblet cell and lacrimal unit damage
USMLE Step 2 CK Exam Tips
- 1Chemical splash to eye = immediate copious irrigation before anything else
- 2Do not check visual acuity before starting irrigation if it delays irrigation
- 3Alkali burns are worse than acid burns because they penetrate deeper by liquefactive necrosis
- 4Continue irrigation until ocular pH normalizes and remains stable after stopping briefly
- 5Remove contact lenses and evert lids/sweep fornices for retained particles
- 6Limbal ischemia is the key poor prognostic sign
- 7Topical anesthetic is appropriate to facilitate irrigation but not for outpatient home use
- 8Painful red eye after chemical exposure is not conjunctivitis — treat as burn emergency
practicetest your knowledge on chemical eye injuryApply what you've learnt with USMLE Step 2 CK-style questions from the iatroX Q-Bank — ophthalmology and beyond.
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