One major cause of eye pain is chemical burns to the eyes; chemical burns account for 5 to 10 percent of injuries to the eyes. Severe chemical burns in the eyes are a medical emergency and can cause permanent vision loss. The severity of the chemical burn varies depending on the chemical involved in the burn, the amount of the chemical that gets into the eye and the length of time that the chemical can react with the eye. There are three general categories of chemical burns: acid burns, alkali (basic) burns and minor burns from chemical eye irritants.
Acids are chemicals with a pH lower than 7, while bases have a pH higher than 7. The lower the pH, the higher the acidity of the chemical, and the higher the pH, the more basic the chemical is. Stronger acids and bases can cause more damage to the eyes than weak acids or bases. In general, alkali burns to the eyes are more dangerous than acid burns. The reason for this is because the alkaline chemicals can generally penetrate deeper into the eye than acids can, so deeper structures of the eye are damaged. Certain strong acids, like hydrofluoric acid, are also extremely dangerous, and even acid burns that damage just the corneas can cause serious vision damage. Acids and bases may be found in certain household items, including cleaning products, car batteries and fertilizers. In contrast to acid burns and alkali burns, irritants are chemicals that have a pH around 7. Irritants may cause eye pain and discomfort, but the chance of the eye being permanently damaged are much lower than with acids or bases. Examples of irritants include most cleaning products and pepper spray.
Although chemicals that can cause eye burns can be found in the home, most eye burns from chemicals occur in an industrial setting. In order to prevent chemical burns to the eyes at work, it is important to wear the proper eye protection for the job, such as splash-proof goggles. If a chemical burn occurs in the workplace, there is often an eyewash station that can be used to rinse out the affected eyes for at least 10 minutes; this should be done as quickly as possible while someone calls for medical help. For minor injuries, a doctor may prescribe eye drops. For severe injuries, more extensive medical treatment, including medications and surgery, may be required.