Caustic keratoconjunctivitis

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Background

  • Chemical burn to eye
  • Alkali injuries are more severe than acidic injuries, and are considered an ophthalmologic emergency
  • Prognosis is determined by the extent of injury at the limbus and area/depth of injury to cornea

Caustics

  • Substances that cause damage on contact with body surfaces
  • Degree of injury determined by pH, concentration, volume, duration of contact
  • Acidic agents cause coagulative necrosis
  • Alkaline agents cause liquefactive necrosis (considered more damaging to most tissues)
  • Corrosive agents have reducing, oxidising, denaturing or defatting potential

Alkalis

  • Accepts protons → free hydroxide ion, which easily penetrates tissue → cellular destruction
    • Liquefactive necrosis and protein disruption may allow for deep penetration into surrounding tissues
  • Examples
    • Sodium hydroxide (NaOH), potassium hydroxide (KOH), ammonia (NH3)
    • Found in: bleach, drain openers, oven cleaners, toilet cleaner, hair relaxers

Acids

  • Proton donor → free hydrogen ion → cell death and eschar formation, which limits deeper involvement
    • However, due to pylorospasm and pooling of acid, high-grade gastric injuries are common
      • Mortality rate is higher compared to strong alkali ingestions
  • Can be systemically absorbed and → metabolic acidosis, hemolysis, AKI
  • Examples
    • Hydrochloric acid (HCl), hydrofluoric acid (HF), Sulfuric acid (H2SO4)
    • Found in: auto batteries, drain openers, metal cleaners, swimming pool products, rust remover

Clinical Features

  • Severe ocular pain, blepharospasm, reduced visual acuity
  • Elevated IOP may be seen in alkali injury[1]
  • Altered ocular pH (normal = 7.0-7.2)
  • Appearance
    • Conjunctival injection OR blnnching
    • Chemosis, hemorrhage, epithelial defects
    • Corneal loss OR edema
  • Perilimbal ischemia (white ring around iris)
    • Concerning due to co-location of corneal stem cell layer (re-epitheliazation relies on migration of limbal stem cells)

Roper-Hall classification[2]

Grade Cornea Appearance Limbal Ischemia Prognosis
I Clear None Good
II Hazy/iris details visible <1/3 Good
III Opaque/iris details obscured 1/3-1/2 Guarded
IV Opaque/iris details obscured >1/2 Poor

Differential Diagnosis

Caustic Burns

Conjunctivitis Types

Unilateral Red Eye

^Emergent diagnoses

^^Critical diagnoses

Evaluation

  • Generally a clinical diagnosis

Management

  • Irrigation
    • Immediate irrigation is the most important treatment for caustic ocular injury, and should be started before comprehensive evaluation
    • Irrigate affected eye(s) with copious amounts of fluid (no consensus on volume or length of time)[3]
    • NS, LR, or BSS (Buffered Saline Solution) preferred in the hospital setting[4], but tap water is acceptable, especially in pre-hospital setting.
    • Goal is to remove caustic agent and restore normal ocular pH (7.0-7.2)
    • Do NOT attempt to neutralize pH by adding base to an acidic burn or acid to an alkali burn
    • Use of morgan lens or eyelid speculum will assist with getting more fluid in contact with cornea
  • Remove particulate matter
    • Evert both lids, remove any visible particulate matter with cotton-tipped applicator
  • Anesthesia
    • Topical anesthetic (e.g. tetracaine) to help with discomfort.
    • Other options include cycloplegics (e.g. atropine, cyclopentolate), IV/IM/PO analgesics
  • Antibiotics
    • Erythromycin ophthalmic ointment QID for minor burns
    • Topical fluoroquinolone for more severe burns
  • Control inflammation
    • Topical steroids - prednisolone 1% ophthalmic QID for 1 week[5]
    • Limit topical steroid use to 10 days to avoid corneal breakdown.[6]
  • Ophtho consultation for all but minor burns (Severe exposures may require debridement or other surgical intervention)

Disposition

  • Admit for:
    • Pediatric patient
    • Corneal haziness, opacity, or limbal ischemia (paleness at limbus)
  • Discharge with 24hr ophthalmology follow-up if only has corneal epithelial injury
    • Encourage use of artificial tears and other lubricating eyedrops

See Also

References

  1. Lin, M.P., et al., Glaucoma in patients with ocular chemical burns. American journal of ophthalmology, 2012. 154(3): p. 481-485 e1.
  2. Gupta N et al. Comparison of Prognostic Value of Roper Hall and Dua Classification Systems in Acute Ocular Burns. Br J Ophthalmol. 2011;95(2):194-198. http://www.medscape.com/viewarticle/739100.
  3. Chau JP, Lee DT, Lo SH. A systematic review of methods of eye irrigation for adults and children with ocular chemical burns. Worldviews Evid Based Nurs. 2012 Aug;9(3):129-38.
  4. Herr RD, White GL Jr, Bernhisel K, Mamalis N, Swanson E. Clinical comparison of ocular irrigation fluids following chemical injury. Am J Emerg Med. 1991 May;9(3):228-31.
  5. Dohlman, C.H., F. Cade, and R. Pfister, Chemical burns to the eye: paradigm shifts in treatment. Cornea, 2011. 30(6): p. 613-4.
  6. Donshik, P.C., et al., Effect of topical corticosteroids on ulceration in alkali-burned corneas. Archives of ophthalmology, 1978. 96(11): p. 2117-20.