The most common injuries involving the surface of the transparent dome on the front surface of the eye (cornea) are scratches (abrasions) and foreign bodies (objects). Foreign bodies in the cornea leave abrasions behind after they are removed. Most of these injuries are minor.
Particles are common causes of corneal abrasions. Particles can be dispersed via explosions, wind, or working with tools (for example, grinding, hammering, or drilling). Tree branches or falling debris can also cause corneal abrasions. Another common source of abrasions is contact lenses. Poorly fitting lenses, lenses worn when the eyes are dry, lenses that have been incompletely cleaned and that have particles attached to them, lenses left in the eyes too long, lenses left in inappropriately during sleep, and forceful or inept removal of lenses can result in scratches on the surface of the eyes. Most corneal abrasions heal without developing infections (such as conjunctivitis and corneal ulcers), but those contaminated with soil or vegetable matter (for example, an injury caused by a tree branch) are more likely to become infected.
Corneal abrasions and foreign bodies usually cause pain, tearing, and a feeling that there is something in the eye. They may also cause redness (due to inflamed blood vessels on the surface of the eye) or, occasionally, swelling of the eye and eyelid. Vision may become blurred. Light may be a source of irritation or may cause the muscle that constricts the pupil to undergo a painful spasm.
Injuries that penetrate the eye may cause similar symptoms. If a foreign object penetrates the inside of the eye, fluid may leak out.
Diagnosis and Treatment
Prompt diagnosis and appropriate treatment can help prevent infection. The diagnosis is based on the person's symptoms, the circumstances of the injury, and the examination.
The surface of the eye is usually numbed with an anesthetic drop (such as proparacaine). An eye drop containing a dye (fluorescein) that glows under special lighting makes surface objects more visible and reveals abrasions. Using a slit lamp (see Diagnosis of Eye Disorders: Slit-Lamp Examination) or other magnifying instrument, the doctor then removes any remaining foreign objects. Often the foreign object can be lifted out with a moist sterile cotton swab or flushed out with sterile water (irrigation). If the person is able to stare without moving the eye, foreign objects that cannot be dislodged easily with a swab can often be removed painlessly with a sterile hypodermic needle or a special instrument. When iron or steel foreign bodies are removed, they can leave a ring of rust, which may need to be removed with a sterile hypodermic needle or a low-speed rotary sterile burr (a small surgical tool with a tiny, rotating, grinding, and drilling surface). Sometimes a foreign body is trapped under the upper eyelid. The eyelid must be flipped over (a painless procedure) to remove the foreign body. Doctors may also gently rub a sterile cotton swab over the inside of the eyelid to remove any tiny particles that may not be visible.
Corneal abrasions are treated similarly whether or not a foreign body was removed. Usually, an antibiotic ointment (for example, bacitracin with polymyxin B) is given for a few days to prevent infection. Large abrasions may require additional treatment: The pupil is kept dilated with cycloplegic eye drops (such as cyclopentolate or homatropine). These drops prevent painful spasm of the muscles that constrict the pupil. Pain can be treated with oral drugs such as acetaminophen or occasionally with acetaminophen with oxycodone. Some doctors give diclofenac or ketorolac eye drops to help relieve pain, but care must be taken because these drugs could rarely cause complications such as a type of corneal scarring (called corneal melting). Anesthetics that are applied directly to the eye, although they relieve pain effectively, should not be used after evaluation and treatment because they can impair healing. Eye patches may increase the risk of infection and usually are not used, particularly for abrasions that result from a contact lens or an object that may be contaminated with soil or vegetable matter.
Fortunately, the surface cells of the eye regenerate rapidly. Even large abrasions tend to heal in 1 to 3 days. A contact lens should not be worn for 5 days after the abrasion heals. A follow-up examination by an ophthalmologist 1 or 2 days after the injury is wise.
Protective eyewear (safety glasses) can help prevent many injuries.
Intraocular Foreign Bodies
Intraocular (inside the eye) foreign bodies are rare. They occur when a foreign object penetrates the eye. A serious infection can develop.
Explosions can cause intraocular foreign bodies. So can anything with a metal-on-metal mechanism. Explosions and certain tool mechanisms often cause small particles to fly in a person's face. For example, using high-speed machines (such as drills and saws) or hammering a nail or other metal object with a hammer can produce white-hot particles of metal that resemble sparks. Any of these white-hot particles can enter the unprotected eye and become embedded deep within it.
Foreign bodies that penetrate the inside of the eye can infect the inside of the eye (endophthalmitis).
Symptoms and Diagnosis
During the first hours after injury, symptoms of intraocular foreign bodies may be similar to those of corneal abrasions and foreign bodies. However, people with intraocular foreign bodies may also have a noticeable loss of vision. Fluid may leak from the eye, but if the foreign body is small, the leak may be so small that the person is not aware of it. Also, pain may increase after the first several hours.
When a foreign object has penetrated the eye, an ophthalmologist should examine the person as soon as possible. The eye is examined as for corneal abrasions and foreign bodies by using eye drops that contain a dye that glows under special lighting (fluorescein) and a slit lamp (see Diagnosis of Eye Disorders: Slit-Lamp Examination). The dye and slit lamp make visible any small leaks of fluid from the eye and puncture marks. Any foreign bodies outside of the eyeball are removed. If an intraocular foreign body is suspected after the examination, an imaging study such as computed tomography (CT) is done.
Prevention and Treatment
People with certain occupations or hobbies, particularly those that use grinders, drills, saws, or hammers, should wear protective eyewear (such as face shields, safety glasses, or goggles) to help prevent intraocular foreign bodies and other eye injuries.
Antibiotics such as ceftazidime and vancomycin are given intravenously. If necessary, vomiting can be controlled with drugs that treat nausea. A protective shield (such as a commercially prepared shield or the bottom part of a paper cup) is taped over the eye to avoid unintentional pressure that could further damage the eye. An ophthalmologist should remove the foreign body as soon as possible. Prompt removal reduces the risk of infection. Sometimes a surgical procedure is needed to remove the foreign body.
Last full review/revision January 2013 by Kathryn Colby, MD, PhD