Chemical eye burns fall into three categories based on a measurement of pH. The pH scale ranges from 0-14 and indicates how acidic or alkaline a substance is. The pH of 7 is neutral; the pH of healthy tears is 7.5. A pH less than 7 is acidic while a pH greater than 7 is alkaline.

The three categories of chemical eye burns are:

• Alkali Burns: These burns involve high pH chemicals, and thus are the most dangerous. They are powerful enough to penetrate the eye, and cause damage to its vital inner components. In the worst cases, they can lead to conditions like cataracts and glaucoma and may cause vision loss or blindness. Examples include: ammonia, drain cleaners, oven cleaners and fertilizers.
• Acid Burns: Lower pH burns are less serious than alkali burns, but still dangerous. These burns don’t easily penetrate the eye, but still may cause significant damage to the cornea, with the potential to cause vision loss. Examples include: battery acid, vinegar, and nail polish remover.
• Irritant Burns: These substances are neutral in pH. Examples include many household detergents and pepper spray.

The severity of the burn depends on the chemical, as well as the amount that comes into contact with the eye. The vast majority of burns are treatable but all should be taken seriously.