BACKGROUND: Metallic foreign bodies are a common occurrence in the primary eye care setting. The momentum (mass x velocity) of a foreign body is the primary determinant of the damage the foreign body will cause and the depth to which it will penetrate. The following case describes an event where the foreign body had enough momentum to penetrate Bowman`s membrane but insufficient momentum to enter the anterior chamber. The unique physical and physiological properties of the cornea, and the toxicity and reactivity of different metals provides multiple treatment options for a retained foreign body.
CASE REPORT(S). A 43 year-old white male presented to the clinic 3 days after sustaining a foreign body (FB) injury to his right eye. He reported steady resolution of redness, pain, and photophobia, which had been described as moderate to severe at onset. He treated himself with cold compresses and acetaminophen. The injury occurred when his 22 cal. rifle accidentally discharged as he attempted to close the breech. The patient presented with 20/60 OD and 20/30 OS unaided acuity. Biomicroscopy revealed 3+ conjunctival injection with no obvious lacerations. The corneal epithelium was intact with a FB track within the stroma extending from an entry point just above the visual axis and continuing to the 11 o`clock limbus where a 0.5mm x 1.5mm brass FB was lodged. The anterior chamber was well formed with trace cells and normal iris and crystalline lens. Dilated fundus exam was unremarkable. The patient was to continue palliative treatment and return for consultation to consider FB removal. Gonioscopy determined that the FB had not reached the angle structures or penetrated Descemet`s membrane. Due to the proximity of the FB to the limbal blood supply and the continued low-grade inflammation, the FB was removed under general anesthesia. All post-operative findings were unremarkable.
CONCLUSIONS. Understanding the circumstances in which an injury occurs and the composition of the FB helps to direct the clinician`s diagnostic and treatment decisions. Pain is not always a reliable indicator of the severity of an injury as demonstrated by this patient`s delay in seeking treatment and continuance of his daily routine.