CT Orbit Imaging for Metal Foreign Bodies in the Eye

Indications for CT Orbit in Metal Foreign Body Cases

The American College of Radiology recommends CT orbit for suspected metal foreign bodies in the eye due to its 94.9% sensitivity for detection of intraorbital foreign bodies, especially metallic ones 1, 2, 3
CT orbit should be ordered when there is clinical evidence of ocular penetration or trauma with suspicion of a metallic foreign body 4, 1, 5
CT is superior for detecting and localizing metallic foreign bodies, fractures, soft tissue injuries, hemorrhage, and assessing the extent of globe damage 1, 2

Patients with history of high-velocity projectile injury (e.g., metal working, hammering) should undergo CT orbit 5
Patients with signs of ocular penetration (corneal/scleral laceration, shallow anterior chamber, hyphema) require CT orbit 6, 7
Patients with visual loss, extraocular movement restriction, or periorbital soft tissue swelling after trauma should undergo CT orbit 6, 7

Non-contrast thin-section orbital CT with multiplanar reconstructions is recommended 6, 7
Contrast is typically not needed in the trauma/foreign body setting 6, 7

CT is superior to plain radiography, which is insufficient for detecting orbital pathology 1, 8, 9
MRI is contraindicated when metallic foreign bodies are suspected due to potential movement of the object caused by the magnetic field 6, 7

Wooden foreign bodies may appear hypoattenuating on CT and can be mistaken for air; MRI may be useful as a supplementary imaging modality in these specific cases 1, 2
CT head is only indicated when concurrent head trauma or intracranial abnormality is suspected 1, 5

Reduced visual acuity in the affected eye indicates ocular damage, with a visual acuity of 6/12 in the affected eye compared to 6/6 in the unaffected eye, according to the American Academy of Ophthalmology 10, 11
Mild inflammation suggests ocular trauma, as reported by the American College of Radiology 11

CT scan of orbits and urgent ophthalmological review is the most appropriate next step, with a recommended protocol of non-contrast thin-section orbital CT with multiplanar reconstructions, as suggested by the American College of Radiology 11, 12
Avoid eye manipulation until ophthalmological assessment, including not attempting to evert the lids further and not applying pressure to the eye, as recommended by the American Academy of Ophthalmology 10

Topical antibiotics with eye pad and next-day review is inadequate for a suspected penetrating injury with an irregular pupil, as stated by the American Academy of Ophthalmology 10
Topical antibiotics with review only if symptoms persist is inappropriate given the high-risk presentation, according to the American College of Radiology 11
Referral to ophthalmologist within days to weeks is too delayed for a potential penetrating injury, as recommended by the American Academy of Ophthalmology 10