Background
Corneal foreign body is foreign material on or in the cornea, usually metal, glass, or organic material.
Pathophysiology
Corneal foreign bodies generally fall under the category of minor ocular trauma. Small particles may become lodged in the corneal epithelium or stroma, particularly when projected toward the eye with considerable force.
The foreign object may set off an inflammatory cascade, resulting in dilation of the surrounding vessels and subsequent edema of the lids, conjunctiva, and cornea. White blood cells also may be liberated, resulting in an anterior chamber reaction and/or corneal infiltration. If not removed, a foreign body can cause infection and/or tissue necrosis.
Epidemiology
Frequency
United States
Foreign bodies are one of the most frequent causes of visits for ophthalmic emergencies. Sometimes, the foreign body may not be present at the time of examination, having left the residual corneal abrasion with resultant pain.
Superficial corneal foreign bodies are much more common than deeply embedded corneal foreign bodies. The possibility of an intraocular foreign body must always be considered when a patient presents with a history of trauma.
In major league baseball, 33% of all eye injuries are corneal abrasions; in the National Basketball Association, corneal abrasions account for 12% of all eye traumas.
International
No difference in frequency is observed internationally.
Mortality/Morbidity
Generally, superficial foreign bodies that are removed soon after the injury leave no permanent sequelae. However, corneal scarring or infection may occur. The longer the time interval between the injury and treatment, the greater the likelihood of complications.
If the foreign body fully penetrates into the anterior or posterior chambers, then it is officially an intraocular foreign body. In this case, eye morbidity is much more common. Damage to the iris, lens, and retina can occur and severely damage vision. Any intraocular foreign body can lead to infection and endophthalmitis, a serious condition possibly leading to loss of the eye.
Sex
Similar to other traumatic injuries, the incidence in males is much higher than in females.
Age
Similar to most other traumatic injuries, the peak incidence is found in the second decade and generally occurs in people younger than 40 years.
Prognosis
Good prognosis exists unless a rust ring or scarring involves the visual axis. If infection develops, prognosis is more guarded. Globe penetrating injuries and intraocular foreign bodies are separate categories and have much worse prognoses.
Patient Education
Remind patients of the importance of wearing protective eyewear in any high-risk situation.
Eyes should not be rubbed while working with wood or metal pieces.
If a foreign body enters the eye, the eye should not be rubbed and no attempt should be made by the patient to remove the foreign body.
For excellent patient education resources, visit eMedicineHealth's Eye and Vision Center. Also, see eMedicineHealth's patient education articles Eye Injuries and Foreign Body, Eye.
