Alkali burns are the most dangerous. Alkalis chemicals that have a high pH penetrate the surface of the eye and can cause severe injury. In general, the higher the pH, the more damage will occur. Common alkali substances contain the hydroxides of ammonia, potassium, sodium, calcium, and magnesium. Substances you may have at home that contain these chemicals include lye, cement, lime, and ammonia.
Acid burns result from chemicals with a low pH and tend to be less severe than alkali burns.
The exception is a hydrofluoric acid burn, which is as dangerous as alkali. Acids usually damage the very front of the eye. Common acids causing eye burns include sulfuric acid, sulfurous acid, hydrochloric acid, nitric acid, acetic acid, chromic acid, and hydrofluoric acid. An automobile battery can explode and cause a sulfuric acid burn. This is one of the most common acidic burns of the eye.