Which is worse an alkali eye burn or acid eye burn, and why?

An alkali burn of the eye is worse than an acid burn. The reason for this is that as the acid penetrates the sclera and cornea and other parts of the eye, it coagulates the protiens present (this is a characteristic of proteins) and this impedes the further spread of the acid. Alkalis though do not cause coagulation of protein and hence nothing impedes the further spread of the alkali, causing a worse burn.

Burns damage tissues primarily by denaturing and coagulating cellular proteins and secondarily through vascular ischemic damage. Whether thermal or chemical, the severity of burns results from the depth and degree of epithelial damage and limbal ischemia. If the limbus is affected significantly, the cornea may develop recurrent epithelial defects, and conjunctival invasion onto the cornea may occur due to the loss of stem cells responsible for renewing corneal epithelium.

• Acidic chemicals
  • Common acids causing ocular burns include sulfuric acid, sulfurous acid, hydrochloric acid, nitric acid, acetic acid, chromic acid, and hydrofluoric acid.
  • Automobile battery explosion, which causes a sulfuric acid burn, is perhaps the most common acidic burn of the eye.
  • Hydrofluoric acid may be found at home in rust removers, aluminum brighteners, and heavy-duty cleaners. Certain industries use hydrofluoric acid in brick cleaning, glass etching, electropolishing, and leather tanning. Hydrofluoric acid also is used to control fermentation in breweries.
  • Ocular hydrofluoric toxicity can occur from liquid or gaseous exposure.

• Alkali chemicals
  • Common alkali substances contain ammonium hydroxide, potassium hydroxide, sodium hydroxide, calcium hydroxide, and magnesium hydroxide. Substances that contain such compounds and can be found in a home include lye, cement, lime, and ammonia.
  • Air bags aerosolize sodium hydroxide on inflation and may cause an alkali keratitis. Additionally, sparklers and flares contain magnesium hydroxide and phosphorus.