Exposure of the eyes to chemical alkali can rapidly result in severe injury. Contact of an alkali solution with pH > 11.5 can result in the immediate destruction of epithelial cell membranes in the cornea with denaturation of intracellular enzymes.
Common alkali chemicals involved in ocular exposure:
(1) sodium hydroxide
(2) lime (calcium hydroxide)
(3) ammonia compounds
Phases of alkali injury:
(1) Alkali rapidly penetrates the epithelium of the cornea and conjunctiva after making contact with the eye.
(2) Immediately after the exposure there is pain due to nerve stimulation, followed by anesthesia as the nerve endings are destroyed.
(3) Shortly after the exposure there is lysis of corneal cells with release of chemotactic factors and inactivation of enzymes.
(4) This is followed by a leukocytic infiltration with degranulation and proteolysis.
(5) There is a rapid rise in intraocular pressure.
(6) In more severe injury, the cornea becomes translucent or opaque and the conjunctiva becomes edematous, with involvement of the perilimbal blood vessels resulting in ischemic damage
(7) Ischemic necrosis of conjunctiva or sclera is indicated by blanching, with severe burns resulting in marked whitening of the sclera.
(8) Ongoing injury with recurrent epithelial breakdown and ulceration following the exposure, sometimes occurring months or even years later.
Grading Alkali Burns
The extent of permanent injury is determined by:
(1) the nature and concentration of the alkali, with the pH critical
(2) the length of time before the eye is irrigated
Grading is usually performed about 24 hours after the exposure.
Cornea |
Conjunctiva |
Grade |
no epithelial damage |
no ischemia |
0 |
epithelial damage with faint haziness |
no ischemia |
1 |
hazy but iris detail seen |
ischemia less than one third at limbus |
2 |
total epithelial loss; stromal haze with iris details blurry but still observable |
ischemia of one third to one half at limbus |
3 |
opaque with no view of iris or pupil |
ischemia affects more than one half at limbus |
4 |
where:
• The limbus is point of insertion of the cornea into the sclera.
Complications of Alkali Burns
Possible complications:
(1) corneal scarring with visual handicap
(2) corneal vascularization with visual handicap
(3) corneal ulceration, which may occur long after the exposure
(4) acute or chronic glaucoma
(5) perforation of the cornea or bulb
(6) hypotonic (phthisis bulbi) because of injury to the aqueous forming structures
(7) symblepharon formation
(8) severe dry eye state due to destruction of the openings from the accessory and main lacrimal glands
Grade |
Prognosis |
1 |
good |
2 |
good |
3 |
vision reduced, perforation rare |
4 |
poor with prolonged convalescence |
Specialty: Toxicology, Emergency Medicine, Critical Care, Ophthalmology
ICD-10: ,