Alkali Eye Injury

Exposure to a base (sodium hydroxide, potassium hydroxide, ammonia, calcium hydroxide as lime and plaster, magnesium hydroxide in flares and fireworks, cement). Alkali burns are the commonest and most damaging chemical eye injury.

• Mechanism: hydroxyl ions saponify cell membrane lipids and hydrolyse collagen; ammonia (lipid soluble) penetrates the anterior chamber within seconds; sodium hydroxide causes deep penetration within minutes; lime causes persistence of particles in the fornix with ongoing release.
• Consequences: liquefactive necrosis, corneal stromal haze, endothelial loss, trabecular damage with glaucoma, lens opacity, ciliary body damage (hypotony), limbal stem cell destruction.
• Natural course: acute phase (first 7 days), early repair (days 7 to 21: risk of corneal melt, ulceration, persistent epithelial defect), and late repair (after 3 weeks: scarring, vascularisation, symblepharon, glaucoma).

• Pain, tearing, blepharospasm, loss of vision, redness, and often patient history of splash during cleaning or plastering.
• Epithelial loss, corneal opacity ranging from mild haze to porcelain white cornea, conjunctival blanching at the limbus (ischaemia, scored in clock hours), chemosis, anterior chamber flare, raised intraocular pressure (early prostaglandin release or later trabecular damage), cataract, and lid burns.
• Prognosis markers: extent of limbal ischaemia (more than 50 percent is poor), degree of corneal opacity, and extent of conjunctival involvement.
• Late: corneal vascularisation, conjunctivalisation, recurrent erosions, limbal stem cell deficiency, symblepharon, entropion and trichiasis, dry eye, glaucoma.

• Irrigate immediately before any examination or history taking. Check pH of the fornices (litmus) and repeat after 5 to 10 minutes of cessation of irrigation; continue until pH 7.0 to 7.4.
• Slit lamp examination after irrigation: fluorescein staining of defect, depth of haze, limbal ischaemia, anterior chamber, lens and intraocular pressure, and fornix search for particles (double eversion of lids).
• Anterior segment optical coherence tomography for stromal thickness, and corneal thickness monitoring.
• Daily monitoring of the epithelial defect, corneal thinning, pressure and ischaemia.

• Immediate irrigation at the scene with water for at least 20 to 30 minutes, and in the department continue with 2 to 3 L or more of normal saline or balanced salt solution (Morgan lens or giving set at 1 L per hour) after topical anaesthesia; evert the lids and remove all particulate matter (lime, plaster) with a moist swab or forceps; recheck pH every 10 to 15 minutes after stopping irrigation until stable at 7.0 to 7.4; irrigate for at least 2 hours in severe injury (ammonia and sodium hydroxide).
• Medical therapy for 1 to 3 weeks:
  • Prednisolone acetate 1 percent every 2 hours while awake for the first 7 to 10 days; then taper rapidly or switch to fluorometholone to prevent melt.
  • Atropine 1 percent twice daily.
  • Chloramphenicol 0.5 percent or ofloxacin 0.3 percent four times daily.
  • Ascorbate 10 percent drops every 2 hours and oral ascorbic acid 1 g twice daily.
  • Sodium citrate 10 percent drops every 2 hours.
  • Doxycycline 100 mg orally twice daily for 2 to 4 weeks; oral prednisolone 1 mg/kg for severe injury.
  • Intraocular pressure control: acetazolamide 250 mg four times daily and timolol 0.5 percent twice daily; paracentesis if pressure is critically high with ischaemia.
  • Preservative free lubricants hourly, autologous serum 20 percent every 2 hours, bandage contact lens or amniotic membrane ring to promote epithelial healing and prevent symblepharon (rodding of fornices with glass rod and ointment).
• Surgical: amniotic membrane transplantation within 7 days for moderate to severe (grade 3 and 4) injury; tenonplasty for limbal ischaemia; tarsorrhaphy; glue and bandage lens for impending perforation; penetrating or lamellar keratoplasty for perforation or scar; cultivated or direct limbal stem cell transplantation (autograft from the fellow eye or allograft with immunosuppression) after the eye is quiet at 3 to 6 months; keratoprosthesis for end stage disease.
• Follow up: daily for the first week, then weekly until healed; monitor pressure long term.