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Ball-bearing (BB) pellets measure approximately 4.3 to 4.4 mm in diameter and are usually composed of steel plated with either zinc or copper. When shot from a modern day BB pellet–firing gun, their velocity can exceed 60 m/s, which is fast enough to pierce skin and fracture bone.
BB pellet injuries most commonly affect young males and can cause significant ocular injuries leading to profound permanent and temporary visual loss as a result of globe rupture, optic neuropathy, chorioretinitis sclopetaria, detached retina, vitreous hemorrhage, and/or hyphema.
In cases involving periocular BB pellet injury, the clinician should request imaging to locate the pellet and decide if surgical excision is required, assess the patient’s tetanus status, and provide instructions on the relevance of adequate eye protection to prevent further injuries.
Case Report
A 16-year-old male with no ocular medical history presented to the emergency department hours after being hit in the right eye by a “rock.” The patient was in foster care and had multiple scars on his forearms, arms, and hands. He did not appear keen on disclosing the details of his injury. On examination, the right eye had counting fingers vision at 6 inches and a notable irregularly shaped pupil with a right-sided relative afferent pupillary defect; the left eye had 20/20 vision and was normal on external examination and dilated fundus examination. Extraocular movements were full, and there was a small, central right lower eyelid laceration through the lid margin (Fig. 1). Intraocular pressures were 11 mm Hg OD and 10 mm Hg OS. Slit-lamp examination revealed a minute inferotemporal bulbar conjunctival laceration without injection or presence of a foreign body, a clear cornea with trace amount of flare in the anterior chamber, and a well-centred lens without dislocation or phacodonesis. Dilated fundus examination revealed significant Berlin edema, hemorrhage at the optic disc, and intraretinal hemorrhage along all 4 arterial arcades and within the macula, consistent with chorioretinitis sclopetaria.
Fig. 1Clinical photograph of the patient’s ocular surface showing a full-thickness right central lower lid laceration and an otherwise normal-appearing conjunctiva.
Given that the patient’s examination findings did not corroborate his story of traumatic rock injury, we obtained a computed tomography (CT) scan of the head and orbit, and the scan revealed a BB pellet impacted in the patient’s right anterior inferotemporal orbit, in contact with the globe (Fig. 2, Fig. 2). A second BB pellet was found under the left body of the mandible. The CT scan showed an intact globe without evidence of orbital fractures, retrobulbar hemorrhage, and/or optic nerve transection.
Fig. 2Axial (A) and (B) coronal computed tomography (CT) images of the BB impacted in the inferotemporal subconjunctival space of the anterior orbit, in contact with the globe.
After ruling out an open globe injury based on external examination, B-scan ultrasonography, and CT findings, we decided to examine the inferotemporal aspect of the globe more closely. For this purpose, we administered proparacaine 0.5% drops and instructed the patient to adduct his right eye. Palpation of the globe under the posterior aspect of the right inferotemporal orbital rim revealed a mobile, subconjunctival BB pellet that could be dragged anteriorly by using the index and middle fingers, causing the patient minimal discomfort (Fig. 3, Fig. 3). Once the BB was at its anterior-most location, the patient’s conjunctival laceration allowed the BB pellet to be expelled. The patient experienced no complications during this procedure, and the sclera underneath was intact. The lid laceration was sutured with 6-0 polyglactin through the lid margin for perfect apposition, followed by two interrupted sutures to close the skin and orbicularis muscle. To the best of our knowledge, this is the first description of the manual expression of a BB pellet from the subconjunctival space within the anterior orbit.
Fig. 3A, External photography of the patient’s ocular surface after palpation of the subconjunctival BB pellet just posterior to the lateral orbital rim and anterior displacement of the BB pellet. B, Extraction of the BB pellet from the minute conjunctival laceration.
In the United States, BB pellet injuries affect the eye in up to 12% of cases and can cause globe rupture, iridodialysis, hyphema, retinal detachment, optic neuropathy, and endophthalmitis.
On impact with ocular tissues, high-velocity missiles, such as BB pellets, create direct and indirect shock wave forces that cause retraction of the choroid and retina from underlying sclera (“chorioretinitis sclopetaria”), resulting acutely in extensive intra- and subretinal hemorrhage with overlying breaks and vitreous hemorrhage and chronically in posttraumatic fibrovascular proliferation and scar formation.
Thus, the clinician must perform a thorough eye examination soon after the injury, obtain imaging to localize any foreign body, and assess for any associated soft tissue, bone, or sinus injuries.
The composition of commercially manufactured BB pellets consists of chemically inert steel coated with a zinc or copper alloy. If the BB pellet is not inducing nerve impingement, mechanical restriction of extraocular movements, acute or chronic infection, or a chronic suppurative reaction, it is preferable to leave it in place because any surgical exploration poses potential risks.
The benefit of leaving a metallic foreign body in place must also be balanced with the potential need for a magnetic resonance imaging study at a later date, in light of the theoretical possibility of magnetically induced migration and radiofrequency-induced heating. A recent study concluded that ballistic objects made of lead with copper or alloy jackets appear safe when exposed to magnetic resonance imaging magnetic fields of 1.5, 3, and 7 Tesla (T), whereas ballistic objects containing steel (e.g., BBs) may pose a danger if located adjacent to critical body structures.
After the initial injury has been treated, or a decision has been made to manage the patient conservatively, the clinician must emphasize the use of protective polycarbonate eyewear, determine the patient’s tetanus status given the small but not insignificant risk of fatal complications from a foreign body–related tetanus injury, and have an earnest discussion with the patient about the visual prognosis.
As our case also demonstrates, high-velocity BB pellet impact with ocular tissues can result in chorioretinitis sclopetaria, caused by shock wave forces, resulting in retraction of the choroid and retina from the underlying sclera. In view of this association, further imaging, such as CT, is indicated in traumatic cases where diffuse intraretinal, subretinal, and optic disc hemorrhaging has been detected, especially when the patient’s examination findings do not corroborate the history of the injury given by the patient. As our case further highlights, patients with a BB pellet lodged in the anterior orbit could benefit from manual expression of the foreign object in the absence of an open globe injury. Alternatively, the surgeon could administer a local anesthetic in the setting of the emergency room or the minor treatment room and use a surgical tray to better control the opening of the conjunctiva. These options may spare patients the expense and potential risks associated with a surgical intervention, allowing adequate care in a non–operating room setting.
Disclosure
The authors have no proprietary or commercial interest in any materials discussed in this article.
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