(See also Overview of Eye Injuries.)
The eyelids close quickly in a reflex reaction to protect the eyes from harm. However, irritating or harmful chemicals still sometimes get onto the surface of the eye, causing chemical burns.
The most dangerous chemical burns involve strong acids or alkali. Alkali burns tend to be more serious than acid burns. Alkali substances include lye and are most commonly found in lime products, concrete, plaster and mortar, oven and drain cleaners, dishwasher detergent, and fertilizers. Burns may involve liquids, which splash, or, less commonly, powdered material, which can blow into the eyes.
Severe chemical burns of the transparent dome on the front surface of the eye (cornea), especially alkali injuries, can lead to scarring, perforation of the eye, infection, and blindness.
Chemical burns to the eye are very painful. Because the pain is so great, a person tends to keep the eyelids closed. Closed eyelids keep the substance against the eye for a prolonged period, which may worsen the damage.
The blink reflex usually causes the eye to close in response to heat. Thus, thermal burns tend to affect the eyelid rather than the conjunctiva or cornea. Thermal burns of the conjunctiva or cornea are usually mild and may cause no lasting damage to the eye.
Wearing safety glasses or a face shield when handling potentially hazardous materials is essential to help prevent burns.
A chemical burn of the eye is treated immediately, even before medical personnel arrive. The eye is opened and flushed (irrigated) with water or saline. When burns are caused by strong acids or alkali or other severely caustic substances, the eye should be irrigated continuously for at least 30 minutes or until the pH (a measure of the acidity or alkalinity) of the eye is normal. Irrigation can be continued where it began, in an ambulance, or in an emergency department. Because pain may make it difficult for the person to keep the injured eye open, another person may have to hold the eyelid open while the eye is irrigated.
A doctor or other health care practitioner can instill an anesthetic drop in the eye to make it much easier to keep the injured eye open. In an emergency department, doctors often use special irrigating devices.
After irrigation, the doctor examines the surface of the eye and the inside of the eyelid and removes any substance still embedded in the tissue. The inside of the eyelid is also swabbed to remove any tiny particles that may not be visible.
A doctor may instill a drop of a drug (such as cyclopentolate or homatropine) that dilates the pupil, relaxing the muscles of the colored part of the eye (iris) and preventing them from having painful spasms. Topical antibiotics (drops or ointment) are used to lubricate the eye and prevent infection. Corticosteroid drops (such as prednisolone) may also be given by an ophthalmologist for a limited period of time.
Although anesthetic eye drops relieve pain, they may also slow healing and are usually not given after the initial irrigation. Pain can be treated with acetaminophen or, if severe, acetaminophen with oxycodone. If the cornea is burned, an antibiotic ointment is put in the eye.
Severe burns need to be treated by an ophthalmologist (a medical doctor who specializes in the evaluation and treatment—surgical and nonsurgical—of eye disorders) within 24 hours to preserve vision and prevent serious complications, such as damage to the cornea and iris, perforation of the eye, and deformities of the eyelid.
In more severe burns, other topical and/or oral drugs such as vitamin C may also be used. Severe burns require frequent eye examinations. Some chemical burns are so severe that surgery is required and even with the best treatment the eye can become blind or visually impaired.
Eyelid burns are treated like other skin burns. Doctors clean eyelid burns and then apply an eye antibiotic to prevent infection. Burns of the conjunctiva or cornea may be painful, so people may need to take analgesics. Doctors may also give cycloplegic eye drops (such as cyclopentolate or homatropine) to prevent painful spasm of the muscles that constrict the pupil, as well as an antibiotic eye ointment to prevent infection.