Abstract
Objective We completed a prospective human cadaveric study to determine the ability of a ball
bearing (BB) pellet to penetrate the orbit and/or surrounding structures.
Methods A single trained sergeant officer discharged an alloy steel air rifle to eight cadaver
orbits from four adult human cadaver heads. Five BB pellets each were aimed at three
locations (caruncle, upper eyelid, or lower eyelid) at 10 cm and 1 m, and then less
specifically, at the orbital region for 3- and 5-m distances. Computed tomography
(CT) of the cadaver heads was performed. Final locations of BB pellets are divided
into three categories: intracranial, surrounding orbital structures including the
pterygopalatine fossa and infratemporal fossa, and orbit.
Results Of 40 BB pellets, 37 penetrated soft tissue and were visualized on CT: 19 (51%) rested
in the intracranial space, 17 (46%) in surrounding orbital structures, and 1 (3%)
within the orbit. The deepest position of a pellet was in the parietal lobe, and most
superficial location anterior to the frontal bone. Pellets discharged from 1 m were
more likely to rest in the intracranial space compared with those from 10 cm (p < 0.001), 3 m (p = 0.011), and 5 m (p = 0.004). The distance of discharge was associated with final pellet location (p = 0.001).
Conclusion BB guns should be considered dangerous and potentially deadly when aimed at the orbit.
Although the thick calvarium can protect the intracranial space from BB penetration,
the orbit may be a vulnerable entry point with relatively low resistance, allowing
penetration of the intracranial and periorbital spaces.
Keywords
ball bearing - cadaver - trauma - orbit
