What's the definition of a chemical eye burns?

Caustic eye injury. The pH of the eye is 7.4, so if a chemical is too acidic or too basic, it can damage the eye if it gets in. It damages the surface of the eye ( a 'burn' ) and can lead to permanent scarring. If you ever get a chemical in your eye that causes instant pain, make sure you pour water in your eye immediately to dilute the chemical and minimize damage.