| Corneal Foreign Body  SIGNS AND SYMPTOMS
Patients who experience a foreign body of the cornea generally present with
mild, moderate, or occasionally severe pain. Sometimes, the discomfort is described as a
scratchiness or the aptly named “foreign-body sensation.” Excessive tearing,
blurred vision and photophobia are also common complaints. Upon inspection, the involved
eye may demonstrate lid edema, focal or circumlimbal conjunctival injection, and a mild to
moderate anterior chamber reaction. The most critical sign is the finding of particulate
matter at the surface of or embedded within the cornea. If the foreign body is metallic,
you’ll often see a rust ring surrounding the object. If the foreign object remained
embedded in the cornea for 24 hours or more, you may see a ring infiltrate surrounding the
site.
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
sets off an inflammatory cascade, resulting in dilation of the surrounding vessels and
subsequent edema of the lids, conjunctiva and cornea. White blood cells are also
liberated, resulting in an anterior chamber reaction and corneal infiltration. A foreign
body, if not removed, can cause infection and/or tissue necrosis.
MANAGEMENT
Initially, it is important to ensure that the object has not perforated the
cornea. If this is not possible simply with slit lamp inspection, you must instill
fluorescein to inspect for aqueous leakage through the wound (Seidel’s sign). If
there’s no penetration, remove the object under topical anesthesia (1-2 gtt 0.5%
proparacaine). A direct stream of sterile irrigating solution may be sufficient to
dislodge some small foreign bodies. If this is not successful, use a flexible-loop foreign
body spud or 25-gauge needle to remove the object under the slit lamp.
CLINICAL PEARLS
When a corneal foreign body encroaches the visual axis,
before proceeding, counsel patients as to the potential loss of acuity due to unavoidable
scarring; this conversation should be well documented to avoid negative clinico-legal
ramifications.
If you are unable to rule out the possibility of a
penetrating ocular injury, apply a shield to the eye and refer the patient immediately to
a nearby hospital or ophthalmology practice.
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