Imaging Protocol

Thin-section axial CT (0.625–1.25 mm) + multiplanar reformation — unenhanced
MRI contraindicated if metallic intraorbital foreign body cannot be excluded
US useful for globe evaluation but contraindicated if ruptured globe is suspected
CT sensitivity for open-globe injury is approximately 70–75%

Systematic Evaluation — Five-Point Approach

Point	Evaluate
1. Bony orbit	All four walls + orbital rim; orbital apex = surgical emergency even with a small fragment
2. Anterior chamber	Decreased depth = corneal laceration or lens subluxation; hyphema = increased attenuation
3. Lens position	Normal / anteriorly subluxed / posteriorly subluxed / dislocated; bilateral dislocation = systemic connective tissue disorder
4. Posterior segment	Vitreous hemorrhage; retinal detachment (V-shape, apex at optic disc); choroidal detachment (lentiform, may cross optic disc); foreign bodies
5. Ophthalmic veins + optic nerve	Dilated superior ophthalmic vein = carotid-cavernous fistula until proven otherwise; optic canal fracture = visual emergency

Orbital Wall Fractures

Fracture	Mechanism	CT Findings	Clinical Notes
Floor blowout	Blunt impact → sudden IOP rise → weakest wall fails	Orbital floor comminution ± herniation of orbital fat/inferior rectus into maxillary sinus; trapdoor in children = hinged fracture	Enophthalmos; inferior rectus entrapment (upgaze diplopia); pediatric trapdoor = surgical emergency — risk of ischemic muscle necrosis
Medial wall blowout	Lamina papyracea of ethmoid is thin	Medial wall disruption; herniation of medial rectus/fat into ethmoid air cells; pneumo-orbit	Medial rectus entrapment; enophthalmos
ZMC / Tripod fracture	Direct zygoma impact	Fractures at 3 sutures: zygomaticofrontal + zygomaticotemporal + zygomaticomaxillary; lateral orbital wall + floor involvement	Cheek depression; infraorbital nerve anesthesia (V2); trismus if zygomatic arch depressed
Orbital apex fracture	High-energy trauma	Fragments at orbital apex; optic canal narrowing	Visual loss = surgical emergency — optic nerve decompression; superior orbital fissure syndrome = CN III/IV/V1/VI

Globe and Intraorbital Injuries

Finding	Imaging Appearance	Clinical Notes
Hyphema / anterior chamber	Blood-fluid level or diffuse increased attenuation in AC; decreased anterior chamber depth = key CT finding for corneal laceration	—
Lens dislocation	Posterior dislocation most common; bilateral = suspect Marfan, Ehlers-Danlos, homocystinuria	—
Open globe (ruptured globe)	Flat tire sign = loss of normal round globe contour (pathognomonic); scleral discontinuity; intraocular air; posterior lens shift	CT sensitivity 70–75%
Retinal detachment	V-shaped hyperdense collection; apex fixed at optic disc; does NOT cross optic disc	Retinal hemorrhage in infant → suspect non-accidental trauma
Choroidal detachment	Biconvex/lentiform; extends from vortex veins to ora serrata; MAY cross optic disc	Distinguishes from retinal detachment
Intraorbital foreign body	Metal: hyperdense, <1 mm detectable; Glass: hyperdense, 1.5 mm detected 96%; Wood/organic: hypodense — may mimic air; geometric margin of low-attenuation collection = suspect wood	—
Carotid-cavernous fistula	Dilated superior ophthalmic vein on NECT = key finding; enlarged cavernous sinus; proptosis; arterialization of periorbital veins; CTA or conventional angiography for confirmation	Clinical triad: pulsatile exophthalmos + chemosis + objective bruit/pulsatile tinnitus; isolated SOV dilation differential includes: cavernous sinus thrombosis, Graves disease, venous varix (correlate clinically)
Optic nerve injury	Optic canal fracture with bony fragment; MRI: T2 prolongation; indirect traumatic optic neuropathy = no fracture but vision loss	—

Orbital apex fracture with any bony fragment compressing the optic nerve is a surgical emergency — alert the clinical team immediately. Dilated superior ophthalmic vein should be flagged as carotid-cavernous fistula until proven otherwise. In children, a trapdoor floor fracture with inferior rectus entrapment requires urgent surgical release to prevent ischemic necrosis.

Reporting Checklist — Orbital Trauma

Orbital walls:
- Floor — intact / fractured; herniation of fat/inferior rectus into maxillary sinus yes / no
- Medial wall — intact / fractured; herniation of medial rectus/fat into ethmoid yes / no
- Lateral wall — intact / fractured
- Roof — intact / fractured
Orbital rim: intact / fractured — ZMC components: zygomaticofrontal / zygomaticotemporal / zygomaticomaxillary
Orbital apex: intact / fractured; optic canal: intact / narrowed; fragment compressing optic nerve yes / no
Globe contour: normal / deformed (flat tire sign); scleral discontinuity present / absent
Intraocular air: present / absent
Anterior chamber: normal depth / decreased; hyphema present / absent
Lens: normal position / anteriorly subluxed / posteriorly subluxed / dislocated; bilateral yes / no
Posterior segment: vitreous hemorrhage / retinal detachment (V-shape) / choroidal detachment (lentiform) / normal
Intraorbital foreign body: present / absent; location (intraocular / intraconal / extraconal); material
Superior ophthalmic vein: normal / dilated — if dilated, evaluate for carotid-cavernous fistula
Optic nerve: normal / compressed / transected
Extraocular muscles: normal / entrapped / displaced
Retrobulbar hematoma: present / absent; proptosis present / absent

Reference

Kubal WS. Imaging of Orbital Trauma. RadioGraphics. 2008;28(6):1729–39.

Orbital Trauma — CT Evaluation and Reporting