Etiology
- Occupational trauma: hammering metal on metal, grinding, nail guns, barbed wire
- High-velocity projectiles: firearms, BB, pellet guns
- Organic materials: tree branches, cacti, other thorny vegetation
- Resulting from lawn mowing or other gardening activity
- Falling and being impaled by object
- Nighttime activities frequently involving running
- Objects that are less than the diameter of the bony orbital entrance that have a pointed end and can be projectile in nature: fish hooks, blow darts, arrowheads
- Blast injuries with resultant building debris, particulate matter, or adjacent anatomy such as teeth
- Motor vehicle related accidents
- Assault with a relatively sharp object, e.g., pencils, ballpoint pens, fingernails, plastic fork, knife
- Protective eyewear frequently not worn
Epidemiology
- More common in children and adults younger than 30
- Males more than females
History
- The event is recorded including seemingly incidental trauma in children. Typically an acute injury, however, organic material can often present late with fistula tracts, granuloma, or abscess formation (Fulcher, Ophthalmology 2002).
- Mechanism of injury (velocity and size of object) with a high index of suspicion when patient reports self-removal of penetrating object as well as in unconscious, intoxicated, and pediatric patients
- Larger, low-velocity objects tend to displace the globe.
- Smaller, higher-velocity objects tend to perforate the globe, ending up in the posterior orbit.
- Composition of foreign body
- Metallic, inorganic, e.g., steel, nickel (Figure 1)
- Nonmetallic, inorganic, e.g., plastic, glass
- Nonmetallic, organic, e.g., tree branch, thorn
- Use of protective eyewear
- Decreased vision or gaze-evoked amaurosis
- Floaters, flashes of light
- Diplopia
- Pain or pain on eye movement
- Fever, chills, neurologic deficits
- Tetanus immunization status

Figure 1. BB-gun pellet. Courtesy Brett Davies, MD.
Clinical features
- External injury might initially seem trivial with small or occult entry wound.
- Decreased vision might indicate associated ocular injury or traumatic optic neuropathy.
- Afferent pupillary defect (APD): traumatic optic neuropathy, optic nerve avulsion
- Decreased ocular motility
- Blepharoptosis
- Orbital fat visualized through eyelid laceration indicating septal penetration
- Periorbital edema and ecchymosis
- Subconjunctival hemorrhage or conjunctival discharge, uveal prolapse
- Perform close inspection of fornices for occult conjunctival entrance wound.
- Chronic, unresponsive or recurrent conjunctivitis following completion of antibiotic course of treatment
- Proptosis or globe dystopia
- Fistula formation with discharge or extruding foreign body
- Subcutaneous palpable mass
- Intraocular injuries: commotio retinae, choroidal rupture, retinal sclopetaria, vitreous hemorrhage, posterior globe indentation, globe perforation
- Mental status changes: subdural hemorrhage, intracranial penetration, pulsatile proptosis
Testing
- Complete eye exam with close attention to vision, pupils, motility, globe integrity, and careful inspection of the periorbita looking for entrance wound(s)
- Medial and lateral canthal tendon integrity
- Culture open wound and any purulence if present
- Do not remove partially embedded objects in an uncontrolled setting without knowledge or visualization of the full length of the object. If necessary, stabilize the object to safely complete imaging in preparation for controlled surgical removal.
- Computed tomography (CT) scan
- Axial, sagittal, and direct coronal views when possible
- Excellent visualization of metal, glass, and stone foreign bodies
- Organic foreign bodies (Figure 2)
- Fresh wood
- Increased water content makes it appear hyperintense or isointense to muscle.
- Dry wood
- Hypointense to fat, can look like air particularly if linear in appearance; absorption coefficients can be helpful in differentiating.
- Eventually becomes more hydrated, appearing more intense over time
- Discuss with the radiologist the possibility of an organic foreign body; expand the window width to 1,000 Hounsfield units; fine axial, coronal, and sagittal cuts (Shelsta, OPRS 2010).

Figure 2. CT scan, organic foreign body.
- Orbital bone defects
- Orbital hemorrhage
- Intracranial injury
- Magnetic resonance imaging (MRI)
- Should never be the initial imaging modality
- Superior soft tissue resolution can help in identification of some wooden foreign bodies.
- Wood appears hypointense on T1-weighted images; ring enhancement with gadolinium might be seen (Shelsta, OPRS 2010).
- Contraindicated for suspected metallic foreign body