Orbital Fracture

The orbital floor and medial wall are the thinnest bony walls of the orbit, making them the weakest points where force is released during blunt trauma — the mechanism behind "blowout" fractures. Orbital fractures result from blunt or penetrating trauma, most often involving the orbital floor, and can be isolated or part of more complex craniofacial trauma.

Blunt trauma transmits force through the incompressible orbital contents, released through fracture of the weakest bony walls. In adults, this typically produces persistent bony displacement allowing fat/muscle herniation into the maxillary sinus. In children, more elastic bone allows a "trapdoor" mechanism: the bone fractures, briefly opens to allow tissue herniation, then springs back, mechanically entrapping tissue (often the inferior rectus) — causing severe ischemia and dramatic findings despite an often unremarkable external appearance, the "white-eyed blowout fracture."³

Presentation ranges from periorbital edema/ecchymosis, diplopia, infraorbital hypoesthesia, and enophthalmos in adults, to severe pain and dramatic motility restriction with minimal external signs in pediatric entrapment.³

Key differentials: isolated muscle contusion/cranial nerve palsy without fracture, traumatic optic neuropathy (a distinct vision-threatening complication), orbital hemorrhage without fracture, and complex craniofacial fracture patterns beyond isolated orbital floor involvement.

Diagnosis combines clinical exam (motility, forced duction testing, sensory exam, globe position) with CT imaging. In adults, standardized indices — RF index (defect size relative to orbital floor length), MH index (herniation height), and MRI index (inferior rectus involvement) — guide surgical versus conservative management decisions.² The "tear-drop sign" on CT indicates tissue herniation through the orbital floor, particularly relevant in pediatric trapdoor fractures.³

In children, confirmed EOM entrapment is a genuine surgical emergency: repair within 24 hours (ideally within 8 hours) significantly improves ocular motility outcomes compared with delayed surgery, with 8-hour repair achieving excellent recovery (Hess area ratio >85%, no residual diplopia).¹ Pediatric patients with soft tissue entrapment only (no sustained oculocardiac reflex) generally improve with conservative management over about 7 weeks — accurate distinction is essential.¹ In adults, standardized radiological indices guide the surgical-versus-conservative decision, with autologous cartilage (nasoseptal or auricular conchal) or alloplastic implants used for reconstruction when surgery is indicated.²

• The "white-eyed blowout fracture" can have minimal external signs but severe entrapment — don't be falsely reassured³
• Pediatric EOM entrapment repair within 24h (ideally 8h) significantly improves motility outcomes¹
• Not all pediatric fractures need emergency surgery — soft tissue-only entrapment often resolves conservatively¹
• The tear-drop sign on CT is a classic entrapment indicator³
• Common pitfall: reassuring a child based on minimal bruising without assessing motility for entrapment
• Common pitfall: delaying referral for confirmed entrapment, risking irreversible ischemic damage