Corneal abrasions are self-limited, superficial epithelial defects.
(See also Overview of Eye Trauma.)
The most common corneal injuries are retained foreign bodies and abrasions. Improper use of contact lenses can damage the cornea. Although superficial foreign bodies often spontaneously exit the cornea in the tear film, occasionally leaving a residual abrasion, other foreign bodies remain on or within the cornea. Sometimes, a foreign body trapped under the upper lid causes one or more vertical corneal abrasions that worsen as a result of blinking. Intraocular penetration can occur with seemingly minor trauma, particularly when foreign bodies result from high-speed machines (eg, drills, saws, anything with a metal-on-metal mechanism), hammering, or explosions.
With a corneal injury, infection generally does not develop from a metallic foreign body. However, corneal scarring and rust deposits can develop. Also, if a corneal foreign body is organic material or abrasions from contact lenses, infection can develop.
If intraocular penetration is not recognized, regardless of foreign body composition, infection within the eye (endophthalmitis) or inflammation (iridocyclitis) may develop.
Symptoms and Signs
Symptoms and signs of corneal abrasion or foreign body include foreign body sensation, tearing, redness, and occasionally discharge. Vision is rarely affected (other than by tearing).
DR P. MARAZZI/SCIENCE PHOTO LIBRARY
Diagnosis
DR P. MARAZZI/SCIENCE PHOTO LIBRARY
slit-lamp examination. A positive Seidel sign indicates leakage of aqueous fluid through a corneal perforation. Patients with multiple vertical linear abrasions should have their eyelids everted to search for a foreign body under the upper lid.
Patients with a high-risk intraocular injury or (more rarely) visible globe perforation, or a teardrop-shaped pupil should undergo CT to rule out intraocular foreign body and be seen by an ophthalmologist as soon as possible. MRI should not be ordered if a metallic foreign body is suspected due to the possibility of the metal moving and causing further injury.
Treatment
For surface foreign bodies, irrigation or removal with a damp, cotton-tipped swab or a small needle
For corneal abrasions, antibiotic ointment and sometimes pupillary dilation
For intraocular foreign bodies, surgical removal
After an anesthetic is instilled into the conjunctiva, clinicians can remove conjunctival foreign bodies by irrigation or lift them out with a moist sterile cotton applicator. A corneal foreign body that cannot be dislodged by irrigation may be lifted out carefully on the point of a sterile spud (an instrument designed to remove ocular foreign bodies) or of a 25- or 27-gauge hypodermic needle under loupe or, preferably, slit-lamp magnification; the patient must be able to stare without moving the eye during removal.
Steel or iron foreign bodies remaining on the cornea for more than a few hours may leave a rust ring on the cornea that also requires removal under slit-lamp magnification by scraping or using a low-speed rotary burr; removal is usually done by an ophthalmologist. Residual corneal abrasions are treated.
Abrasions
> 10 mm2
Eye patches may increase risk of infection and are usually not used, particularly for an abrasion caused by a contact lens or an object that may be contaminated with soil or vegetation. Ophthalmic corticosteroids tend to promote the growth of fungi and reactivation of herpes simplex virus and are contraindicated. Continued use of topical anesthetics can potentially impair healing and is thus contraindicated. Pain can be managed with oral analgesics. Topical anesthetics should not be used. Topical NSAID drops are not approved for this treatment, if used in select patients closer follow-up should be arranged.
The corneal epithelium regenerates rapidly; even large abrasions heal within 1 to 3 days. A contact lens should not be worn until the injury is healed. Follow-up examination by an ophthalmologist 1 or 2 days after injury is wise, especially if a foreign body was removed.
Intraocular foreign bodies
Intraocular foreign bodies require immediate surgical removal by an ophthalmologist. Systemic and topical antimicrobials (effective against Bacillus cereus
A protective shield (eg, plastic or aluminum eye shield or the bottom third of a paper cup) is placed and taped over the eye to avoid inadvertent pressure that could extrude ocular contents through the penetration site. Patches should be avoided. Tetanus prophylaxis is indicated after open globe injuries.
As with any laceration of the globe, vomiting (eg, due to pain), which can increase intraocular pressure, should be prevented. If nausea occurs, an antiemetic is given.
Key Points
Symptoms of corneal abrasion or foreign body include foreign body sensation, tearing, and redness; visual acuity is typically unchanged.
Treat corneal abrasions and foreign bodies by removing foreign material, prescribing a topical antibiotic, and sometimes instilling a cycloplegic.
For intraocular foreign bodies, give systemic and topical antibiotics, apply a shield, control pain and nausea, and consult an ophthalmologist for surgical removal.
