History
The activities of the patient and their surroundings are important. The time and the place of the injury, along with exactly how it occurred, are important. For example, a patient who was working with a high-speed grinding machine is likely to have an intraocular foreign body that may be occult in nature, whereas a patient who was working underneath a car when rust fell gently on the eye is likely to have only an external injury.
Patients may complain of the following:
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Pain (typically relieved significantly with topical anesthesia)
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Foreign body sensation (typically relieved significantly with topical anesthesia)
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Photophobia
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Tearing
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Red eye
Physical
Patients may present with the following:
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Normal or decreased visual acuity
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Conjunctival injection
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Ciliary injection, especially if an anterior chamber reaction occurs
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Visible foreign body
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Rust ring, especially if a metallic foreign body has been embedded for hours to days
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Epithelial defect that stains with fluorescein
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Corneal edema
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Anterior chamber cell/flare
The patients may be asymptomatic if the foreign body is below the epithelial or conjunctival surface. Over a period of a few days, epithelium often grows over small corneal foreign bodies, with a resultant reduction in pain.
If a corneal infiltrate is present, an infectious cause needs to be considered. Foreign bodies can cause a small sterile inflammatory reaction around the foreign object. However, if a large infiltrate, any corneal ulceration, a significant anterior chamber reaction, or significant pain is present, it should be managed as an infection. See Keratitis, Bacterial.
Causes
Corneal foreign body injury can occur just about anywhere. They commonly occur both at home and at work.
Generally, the cause is accidental trauma. The type of trauma helps to determine the likelihood of a superficial versus a deep or even intraocular foreign body.
Materials include small pieces of wood, metal, plastic, or sand.
The injury usually occurs in windy weather or when working with power tools. Dirt, sand, or small portions of leaves frequently are blown into the eye and adhere to the superficial cornea.
Complications
Rust ring usually is due to an iron foreign body and can be removed carefully at a slit lamp using a burr.
Infectious keratitis is common in organic injuries and in neglected cases. It may need to be scraped for smears and cultures. It needs to be treated aggressively with topical antibiotics. If ulceration is unresponsive to antibiotics, consider using riboflavin cross-linking as one study has suggested. [1]
Globe perforation occurs in metal-on-metal and similar high-speed type injuries. It also can occur if a corneal ulcer is neglected. It requires surgical repair.
