Chemical injuries

Chemical injuries

Dr. Mustafa Abdul Hameed IsmailCauses

Range from trivial to potentially blinding.Accidental or assault.2/3rd accidents at work place.Alkali burns are twice as common as acid burns.

Severity of chemical injury is related toProperties of chemicalArea of affected ocular surfaceDuration of exposureRelated effects like thermal injury etc.

Alkalis tend to penetrate more deep than acids?

Pathophysiology

Damage by severe chemical injury occur in following orderNecrosis of conjunctiva and corneal epithelium with disruption and occlusion of the limbal vasculature.Loss of limbal stem cells result in conjunctivalization of corneal surface and persisting epithelial defects.Corneal ulceration and perforation.

Ocular surface wetting disorders, symblephron formation and cicatricial entropion.Corneal stromal opacitiesAC penetration-iritis and lens damage.Ciliary epithelial damage- impaired secretion of ascorbats required for corneal repair.Hypotony and phthisis bulbi.

Management

A chemical burn is the only eye injury that requires emergency treatment without first taking a history and performing a careful examination.

Copious irrigation.Normal saline or Ringer lactate for 15-30 min or neutral.Double aversion of upper eye lid for removal of retained particulate matter Debridement of necrotic areasAdmission for severe injuries.

Grading of severityTo plan appropriate treatment and indicate likely prognosis

Grading on the basis of corneal clarity and severity of limbal ischemia.

Grade 1 Clear cornea ( epithelial damage) no limbal ischemia.- excellent prognosisGrade 2 hazy cornea with visible iris details and < 1/3rd limbal ischemia-good prognosisGrade 3 total loss of corneal epithelium, stromal haze obscuring iris and 1/3 to limbal ischemia.- guarded prognosis.Grade 4 opaque cornea, > limbal ischemia- very poor prognosis.

Medical treatment

Main aims of treatmentReduce inflammationPromote epithelial regenerationPrevent corneal ulceration.

Grade 1and 2Toical antibiotics, topical steroids and cycloplegics.

Steroids Used initially to reduce inflammationMust be tapered off after 7-10 days. May be replaced by NSAIDs.CycloplegicsProphylactic topical antibiotics

Ascorbic aidImproves wound healingPromotes synthesis of mature collaegenCitric acidPowerful inhibitor of neutrophil activity and reduce inflammationTetra-cyclinesEffective collagenase inhibitors, inhibit neutrophil activity and reduce ulcersSymblepharon formation to be prevented.Monitor IOP.

Surgery

Early To promote revascularization of limbusRestore limbal cell populationRe-establish the fornices.Advancement of Tenons capsuleLimbal stem cell transplantationAmniotic membrane grafting

Late Division of conj. bands and treating symblepharonCorrection of eye lid deformityConjunctival or mucous membrane grafting.KeratoplastyKerato-prosthesis.