An orbital blow-out fracture is a fracture of the orbital floor and/or medial wall with an intact orbital rim. It occurs when a sudden rise in intra-orbital pressure – classically a fist, ball or elbow striking the globe – is transmitted to the thin bone of the orbital floor (orbital plate of the maxilla) and medial wall (lamina papyracea of the ethmoid), which fracture and decompress into the maxillary or ethmoid sinus. The floor is the most commonly fractured wall. On CT, look for a bony defect, herniation of orbital fat or the inferior rectus into the maxillary sinus (the “teardrop” sign) and a maxillary-sinus air–fluid level. The key clinical concern is extraocular-muscle entrapment, which – especially in the paediatric “white-eyed” blow-out fracture – can be a surgical emergency.
| Feature | Detail |
|---|---|
| Definition | Fracture of the orbital floor and/or medial wall with an intact orbital rim |
| Most common wall | Orbital floor (maxilla), then medial wall (lamina papyracea) |
| Typical mechanism | Blunt globe trauma; hydraulic and buckling theories |
| Investigation of choice | Non-contrast CT, ≤2–3 mm, bone + soft-tissue windows, coronal & sagittal reformats |
| Cardinal CT signs | Teardrop sign, orbital fat / inferior-rectus herniation, maxillary hemosinus |
| Key complications | Enophthalmos, diplopia, muscle entrapment, infraorbital-nerve injury |
| Surgical emergency | White-eyed blow-out fracture with entrapment / oculocardiac reflex (children) |
Quiz
Which of the following is NOT a feature of this pathology?
- Fracture of medial orbital wall.
- Entrapment of extraocular muscles.
- Herniation of orbital fat.
- Fracture of inferior orbital rim.
To understand the pathologies associated with orbital blow-out fractures, let us first review the anatomy of the orbit in brief.
Anatomy of the orbit
The bony orbit is shaped like a four-sided pyramid, with its base at the orbital rim and its apex directed posteromedially toward the optic canal. It is formed by seven bones and has four walls. The floor (mainly the orbital plate of the maxilla, overlying the maxillary sinus) and the medial wall (the paper-thin lamina papyracea of the ethmoid) are the weakest segments, which is why they are the walls that “blow out” when a sudden rise in intra-orbital pressure is transmitted to them.
| Wall | Main bone(s) | Weak point / relation | Clinical relevance |
|---|---|---|---|
| Floor | Maxilla (orbital plate), zygomatic, palatine | Thin postero-medially; over maxillary sinus; grooved by the infraorbital canal | Most common blow-out site; inferior-rectus entrapment, infraorbital-nerve injury |
| Medial | Lamina papyracea of ethmoid | Paper-thin; over ethmoid air cells | Second most common; medial-rectus entrapment, orbital emphysema |
| Roof | Frontal bone, lesser wing of sphenoid | Over anterior cranial fossa / frontal sinus | Rare; CSF leak, intracranial injury (relatively more in children) |
| Lateral | Zygomatic, greater wing of sphenoid | Strongest wall | Rarely isolated; usually part of a zygomaticomaxillary-complex fracture |
Key imaging features
- Radiograph (frontal PA/AP, Caldwell, Waters, Towne and lateral views) – now largely superseded by CT:
- Black eyebrow sign: air in the superior aspect of the orbit, resembling an eyebrow.
- Soft-tissue teardrop sign: a polypoid soft-tissue density hanging from the roof of the maxillary sinus.
- Air–fluid level in the maxillary sinus (hemosinus).
CT is the study of choice.
- Thin sections (≤3 mm), bone window, non-contrast images.
- Axial & sagittal images: to gauge the distance between the fracture and the orbital apex. If a medial-wall fracture extends to within 1 cm of the optic canal, the optic nerve is at greater risk during surgery and must be approached with caution.
- Coronal images: to gauge the extent and direction of the fracture, especially for floor and roof fractures, and to assess change in orbital shape.
- Thicker soft-tissue-window slices to assess retrobulbar fluid, subperiosteal blood, extraocular muscles and optic-nerve injury. Maxillary hemosinus predicts an orbital-floor fracture (negative predictive value 99.7% according to Huang et al.).
- Multiplanar and 3D reconstructions to assess asymmetry and provide surgical guidance.
- Orbital-volume measurement: an increase from bony widening predicts late enophthalmos once oedema settles.
- Increased chance of late enophthalmos is predicted by the following CT findings:
- Fracture area ≥2 cm²
- Involvement of ≥25–50% of the medial or inferior wall
- Collapsed internal orbital buttress or convex junctional bulge
- Herniated soft-tissue volume >1.5 mL (each ~1 mL increase in orbital volume corresponds to roughly 0.8–0.9 mm of enophthalmos).
A guide to where to look for the ‘internal orbital buttress’ or ‘convex junctional bulge’ is shown below:
- CT also helps exclude foreign bodies and characterise them – e.g. wood measures −100 to −200 HU and increases in density over time as oedema accumulates.
- MRI:
- T2-weighted and contrast-enhanced fat-suppressed sequences.
- Exclude ferromagnetic foreign bodies before MRI.
- Best for globe injury, subperiosteal blood, retrobulbar fluid and optic-nerve injury.
- Ultrasound: may be used to assess intraocular structures.
| Modality | Key signs |
|---|---|
| Radiograph (limited) | Teardrop soft-tissue polyp under the maxillary-sinus roof, black-eyebrow orbital emphysema, maxillary air–fluid level |
| CT (study of choice) | Bony defect, fat/muscle herniation (teardrop sign), maxillary hemosinus, orbital emphysema, and rounding or malposition of the inferior rectus suggesting entrapment |
| MRI (problem-solving) | Muscle entrapment, subperiosteal blood, retrobulbar fluid, globe and optic-nerve injury |
Pathophysiology
A fracture of the walls of the orbit with an intact orbital rim is called a blow-out fracture. Two mechanisms are described: the hydraulic theory (a sudden rise in intra-orbital pressure from the retropulsed globe blows out the thin floor/medial wall) and the buckling theory (a force applied to the orbital rim is transmitted posteriorly and buckles the floor). Both often coexist.
Mechanism of injury:
White-eyed blow-out fracture (WEBOF) & the oculocardiac reflex
In children the elastic orbital floor snaps back after impact, trapping the inferior rectus and orbital fat like a trapdoor (a greenstick pattern). The white-eyed blow-out fracture (WEBOF) is a trapdoor fracture with soft-tissue or muscle entrapment but minimal external signs – a quiet “white” eye without the expected bruising or swelling – so it is easily overlooked. Up to a third of paediatric cases are initially missed or misdiagnosed. Suspect it when a child has restricted vertical gaze, marked eye pain and nausea or vomiting after facial trauma.
The oculocardiac reflex (OCR) is a trigeminovagal reflex triggered by traction on the entrapped muscle, producing bradycardia, nausea, vomiting and sometimes syncope, and is worsened by attempted upgaze. Because these symptoms mimic head injury and raised intracranial pressure, the diagnosis is frequently delayed. The OCR is a surgical emergency; it was first highlighted as an indication for urgent repair by Sires et al. (1998).
On imaging, a trapdoor/WEBOF may show only a subtle linear floor fracture with a small herniating teardrop of tissue, and the muscle may appear near-normal in position – so clinical signs of entrapment outweigh imaging. Prolonged entrapment risks ischaemic muscle fibrosis (a Volkmann-type contracture) and permanent diplopia; urgent release, typically within 24–48 hours, gives the best motility outcomes.
| Feature | Adult blow-out fracture | Paediatric white-eyed (WEBOF) |
|---|---|---|
| Bone pattern | Comminuted / open-door defect | Linear trapdoor (greenstick) |
| External signs | Ecchymosis, oedema, “black eye” | Minimal – a quiet “white eye” |
| Muscle entrapment | Less common | Common (inferior rectus) |
| Oculocardiac reflex | Uncommon | May be prominent |
| Timing of repair | Elective; within ~2 weeks if indicated | Urgent; within 24–48 hours |
Imaging recommendation
High-resolution CT with thin sections, coronal and sagittal reformats, bone and soft-tissue windowing, and multiplanar/3D reconstructions.
Top differential diagnoses
| Differential | Discriminating feature |
|---|---|
| Orbital haematoma without fracture | Retrobulbar soft-tissue density but intact bony walls |
| Other orbital / midface fractures | Rim, roof, lateral wall or zygomaticomaxillary-complex involvement |
| Congenital dehiscence of the lamina papyracea | Smooth, corticated defect without adjacent haemorrhage or sinus opacification |
Clinical features
- Symptoms and signs:
- Decreased visual acuity.
- Enophthalmos – posterior displacement of the intact globe.
- Diplopia – due to extraocular-muscle entrapment.
- Orbital emphysema – when the fracture communicates with a paranasal sinus.
- Paraesthesia over the malar region – due to infraorbital-nerve injury.
- Epistaxis and eye swelling, especially on exertion (e.g. nose-blowing).
- Deepened supraorbital crease and narrowed palpebral fissure.
- Bradycardia, nausea or vomiting (oculocardiac reflex) – a red flag for muscle entrapment, especially in children.
- Age/sex predilection: more common in young males, who are more prone to orbital trauma; in females it may also result from intimate-partner violence.
- Associations: zygomatic-arch fractures, Le Fort type II or III, and other orbital fractures.
Classification system
A) Broad classification
| Type | Description | Key point |
|---|---|---|
| Open-door | Large, displaced, comminuted defect | Often less entrapment; diplopia may be minimal, so its absence does not exclude a significant injury |
| Trapdoor | Linear, hinged, minimally displaced; bone recoils and traps tissue | Muscle/fat entrapment; the “white-eyed” pattern in children; urgent |
B) Isolated floor OR medial-wall fractures
| Subtype | Description | Typical site |
|---|---|---|
| Hinged | A bent fragment stays attached via intact periosteum | More common in floor fractures |
| Punched-out | The entire fractured fragment is free | More common in medial-wall fractures |
C) Combined floor + medial-wall fractures
| Subtype | Description |
|---|---|
| Simple (~60%) | No collapse of the internal orbital buttress |
| Complex | Collapse of the internal orbital buttress with a junctional bulge – greater orbital-volume change and loss of bony landmarks; guides the choice of implant at reconstruction |
A guide to where to look for the ‘internal orbital buttress’ or ‘convex junctional bulge’ is shown in the image under the CT findings above.
Etymology and synonyms
Termed a “blow-out” fracture because the walls of the orbit are blown outward into the adjacent sinus by the sudden rise in intra-orbital pressure. Synonyms include orbital floor fracture and, for the paediatric entrapped variant, the white-eyed blow-out fracture.
Treatment
- Immediate clinical examination and high-resolution CT are warranted.
- Urgent lateral canthotomy and cantholysis if there are signs of orbital compartment syndrome / raised intraocular pressure.
- Observation / medical management is reasonable when ALL of the following are true:
- Enophthalmos <2 mm and no significant hypoglobus.
- Floor defect <50% (or <2 cm²).
- No extraocular-muscle or orbital-tissue entrapment.
- No troublesome diplopia in primary or downgaze.
- Medical management includes analgesia, nasal decongestants, avoidance of nose-blowing, and a short course of oral steroids and antibiotics as needed.
- Surgery is indicated for:
- White-eyed blow-out / trapdoor fracture with muscle entrapment – urgently, within 24–48 hours, especially in children.
- Oculocardiac reflex (bradycardia, nausea, syncope) – emergently.
- Persistent diplopia in primary or downgaze with entrapment.
- Large defect (>50% of the floor or ≥2 cm²) or established/cosmetically significant enophthalmos – typically repaired within about 2 weeks, before fibrosis sets in.
- Post-operative CT is important to confirm implant position and exclude residual entrapment that would prompt revision.
- A multidisciplinary team (ophthalmology, otolaryngology, plastic and maxillofacial surgery) is recommended, with follow-up continued after discharge.
References
Single best review article
Other references
- Nguyen VD, Singh AK, Altmeyer WB, Tantiwongkosi B. Demystifying Orbital Emergencies: A Pictorial Review. RadioGraphics. 2017;37(3):947-962. PMID: 28556764.
- Kubal WS. Imaging of orbital trauma. RadioGraphics. 2008;28(6):1729-1739. PMID: 18936032.
- Jordan DR, Allen LH, White J, Harvey J, Pashby R, Esmaeli B. Intervention within days for some orbital floor fractures: the white-eyed blowout. Ophthalmic Plast Reconstr Surg. 1998;14(6):379-390. PMID: 9842557.
- Sires BS, Stanley RB Jr, Levine LM. Oculocardiac reflex caused by orbital floor trapdoor fracture: an indication for urgent repair. Arch Ophthalmol. 1998;116(7):955-956. PMID: 9682717.
- Amarath-Madav R, Adamkiewicz D, Bigler D, Yu JC, Lima MH. White-Eyed Orbital Blowout Fracture With Oculocardiac Reflex Secondary to Extraocular Entrapment in a Pediatric Patient. J Craniofac Surg. 2022;33(7):e767-e771. PMID: 36109010.
- Koenen L, Waseem M. Orbital Floor Fracture. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; updated 2023.
- Blowout! Managing the orbital floor fracture. American Academy of Ophthalmology, EyeNet, 2016.
- Iowa Head and Neck Protocols: Facial Fracture Management Handbook – Orbital blowout fractures.
Case co-authored by TeamGyan Member Dr. Bhargavi Sovani. Illustrations by Dr. Bhargavi Sovani. Annotated image by Dr. Disha Lokhandwala.
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