Corneal Burns (Chemical Injury)

Definition:

Corneal burn is an eye injury that results from a chemical coming in contact with the eye and causing extensive damage to the ocular surface, especially cornea.

Chemical injury to the eye is truly an ophthalmic emergency that needs immediate attention. Corneal burn may result from any kind of chemical coming in contact with the eye. Majorly, strongly basic (alkaline) compounds or acidic compounds cause serious eye injury.

Corneal burns majorly occur in young males working in industries that deal with chemicals like building materials and cleaning agents. A very minor number of corneal burns occur accidently in homes.

Causes of Chemical injury

Most of the corneal burns occur due to exposure of eye with acidic or alkaline chemicals. Out of these two too, alkali injuries are more common and deleterious because alkali can penetrate tissues more rapidly than acids.

• Alkaline chemicals

Common sources of alkali that can lead to corneal injury are as follows:

• • • • Cleaning products (e.g. ammonia)
      • Fertilizers (e.g. ammonia)
      • Drain cleaners (e.g. lye)
      • Cement, plaster, mortar (e.g. lime)
      • Airbag rupture (e.g. sodium hydroxide)
      • Fireworks (e.g. magnesium hydroxide)
      • Potash (e.g. potassium hydroxide
• Acidic chemicals

Common sources of acids that can lead to corneal injury are as follows:

• • • • Battery acid (e.g. sulfuric acid)
      • Bleach (e.g. sulphurous acid)
      • Glass polish (e.g. hydrofluoric; behaves like alkali)
      • Vinegar (e.g. acetic acid)
      • Chromic acid
      • Citric acid
      • Hydrochloric acid

• Irritants

Irritants are the substances with neutral pH that can cause discomfort to the eye rather than any actual damage. It includes:

• • • • Most of the household detergents
      • Pepper spray

High risk industries or employees for corneal burns/chemical injuries

• Chemical laboratories
• Machine factories
• Agriculture workers (farmers) and labourers
• Construction workers
• Fabric mills
• Automotive repair facilities
• Cleaning and sanitizing crews

Symptoms of Chemical injury

Symptoms of chemical injury specifically depend upon kind of chemical and the severity of the exposure. It may include any or all of the following:

• Stinging or burning sensation in the eye
• Extreme pain and discomfort in the eye
• Foreign body sensation
• Blurred vision
• Excessive tearing
• Inability to keep the eye open
• Photophobia
• Red eye(s)
• Eye irritation
• Discoloration of conjunctiva
• Inflammation of conjunctiva
• Swelling of the eyelids
• Blepharospasm or abnormal contraction or twitch of the eyelid
• Decreased visual acuity
• Bilateral chemical exposure is especially devastating and often result in complete visual disability

Primary prevention for corneal burns

As most of these corneal burns or injuries are due to occupational requirements and occur majorly at work, protective eye/face shields, safety goggles or glasses are mandatory while working in any chemical industry. It is also necessary to always follow chemical and cleaning product instructions while using them.

Diagnosis of Chemical injury

Before performing a thorough physical examination of the eye, affected eye is properly irrigated to neutralise the pH of the eye surface. After this, under topical anaesthesia, a thorough eye examination is performed to evaluate the clarity and integrity of the cornea, degree of limbal ischemia, and IOP. Diagnostic tests may include a fluorescein evaluation.

Treatment of Chemical injury

As it is an emergency condition, immediate and prolonged irrigation of the affected eye is the first and foremost step performed by an eye doctor. This is followed by aggressive early management and close long-term monitoring to promote ocular surface healing and to provide the best opportunity for visual rehabilitation. The common goals of chemical injury management include the following:

• Removing the offending agent by irrigation of eye with a sterile balanced buffered solution like normal saline
• Promote ocular surface healing by
  • Placement of a therapeutic bandage contact lens
  • Artificial tear supplements
  • Topical antibiotic ointment
  • Topical steroids
  • Topical and oral ascorbate
  • Collagenase inhibitors
  • Cycloplegic agents such as atropine or cyclopentolate to ease discomfort
  • Platelet rich plasma eye drops
• Controlling inflammation by
  • Topical steroids
• Preventing infection by prophylactic topical antibiotics
• Controlling IOP by the use of aqueous suppressants
• Visual rehabilitation by surgical procedures like:
  • Amniotic membrane transplantation
  • Debridement of necrotic conjunctival/corneal tissue
  • Limbal stem cell transplant
  • Cultivated oral mucosal epithelial transplantation (COMET)
  • Penetrating keratoplasty with or without cataract extraction
  • Boston Keratoprosthesis

Complications of Corneal burns

It is a serious condition that needs regular follow up with the eye care doctor. If neglected, it can lead to following complications:

• Corneal perforation
• Corneal ulcer
• Glaucoma
• Cataracts
• Dry eye
• Damage to the eyelids or palpebral conjunctiva
• Blindness