A corneal foreign body is a small foreign body on the surface of or embedded in the corneal stroma. A foreign body on the cornea is often associated with ocular trauma, which is most common in young male patients. Very often, the patient was not wearing protective eyewear at the time of injury.

Patients will typically present with severe ocular discomfort, complaining of a foreign body sensation, tearing, and, at times, reduced vision. Patients will almost always be able to relay exactly when the object, and sometimes what object, came into contact with the eye. At times, the patients will even be able to see the foreign body on the cornea. It is essential to check the vision in both eyes.

Ocular siderosis can occur when a foreign body deposits iron in the eye. Typically, iron granules are most prominent in the deeper cornea, but they may be deposited in any corneal layer. Ocular siderosis can develop days to years after the inciting trauma.