When blunt external force is applied to the eye, the orbital bones may fracture. The orbital floor and medial wall are very thin and are common sites for this condition. It is called an orbital blowout fracture because the bone is displaced significantly toward the paranasal sinuses.
Approximately 10% of all facial fractures are isolated orbital wall fractures, and the orbit is involved in 30–40% of all facial fractures. 2) Isolated orbital floor fractures account for 22–47% of all orbital fractures. 2)
In terms of sex and age distribution of injured patients (analysis of 268 cases), 72% were male and 28% female, with an average age of 36 years. 2)
The orbital floor and medial wall are particularly thin and prone to fracture.
| Site | Bone thickness characteristics |
|---|---|
| Orbital floor (infraorbital nerve canal area) | Approximately 0.23 mm (extremely thin) |
| Orbital floor (posteromedial area) | Average 0.37 mm |
| Orbital floor (lateral area) | Average 1.25 mm |
| Medial orbital wall (lamina papyracea) | Thinnest among orbital walls |
In medial orbital wall fractures, the lamina papyracea is damaged. Isolated occurrence is relatively rare, and it often occurs together with orbital floor fractures or as part of a complex fracture.
Fractures are classified into open and closed types based on imaging. In open-type fractures, bone fragments and soft tissues are significantly displaced into the paranasal sinuses. In contrast, closed-type fractures show subtle imaging changes despite prominent clinical symptoms, and the missing rectus sign, where the entrapped extraocular muscle appears to disappear at the fracture site, is characteristic. Closed-type (trapdoor) fractures are more common in young individuals due to higher bone elasticity.
Both are types of orbital blowout fracture and are not separate diseases. Orbital floor fractures mainly cause vertical eye movement disorders and hypoesthesia of the cheek and upper lip. Medial orbital wall fractures primarily cause horizontal eye movement disorders, epistaxis, and subcutaneous emphysema. Combined fractures are also common.
In closed fractures, which are more common in young individuals, systemic symptoms such as severe eye pain, nausea, vomiting, syncope, and bradycardia due to the vagal reflex are frequently associated. Caution is required as these may be misdiagnosed as symptoms of increased intracranial pressure.
Preoperative clinical findings (among 262 cases): enophthalmos 33.6%, diplopia 65.8%, limitation of eye movement 55.1%, and infraorbital nerve hypoesthesia 46.2%. 2)
The characteristics of findings by fracture type are shown below.
Open Fracture
Displacement of bone fragments: Bone fragments and soft tissue are significantly displaced into the paranasal sinuses.
Enophthalmos: The eyeball moves posteriorly due to increased orbital volume. It becomes more prominent as swelling subsides.
Prognosis: If there is no incarceration, the prognosis for eye movement is relatively good.
Closed Fracture (Trapdoor)
Subtle imaging changes: Slight displacement at the fracture site or the missing rectus sign are characteristic findings.
Associated systemic symptoms: Vagal reflex due to tissue incarceration causes severe eye pain, nausea, vomiting, syncope, and bradycardia.
High urgency: If accompanied by extraocular muscle entrapment, there is a risk of muscle necrosis, and emergency surgery is indicated.
Orbital compartment syndrome (retrobulbar hemorrhage): Causes painful proptosis, increased intraocular pressure, and decreased vision due to optic nerve compression. It is a rare but possible emergency in severe cases.
When an extraocular muscle is incarcerated in the fracture site, the oculocardiac reflex (vagal reflex) occurs, causing nausea, vomiting, and bradycardia. It is easily mistaken for symptoms of increased intracranial pressure, and transfer to neurosurgery or pediatrics may delay diagnosis. In children presenting with vomiting after trauma, orbital fracture should be actively suspected.
Blunt trauma to the eye or periorbital area is the cause. Causes of injury (analysis of 268 cases): assault 35.1% (most common), falls 21.6%, sports 19.0%, traffic accidents 13.8%, workplace accidents 1.1%. 2)
There are two theories regarding the mechanism of fracture.
Hydraulic theory
Increased intraorbital pressure due to impact: A fist or ball directly strikes the eyeball, displacing it posteriorly.
Rupture of the weakest point: The sudden rise in intraorbital pressure causes the thinnest area just above the infraorbital neurovascular bundle to blow out.
Soft tissue herniation: Orbital contents herniate into the paranasal sinuses through the fracture site.
Buckling theory
Propagation of pressure waves: Pressure waves generated by blunt trauma to the cheek propagate posteriorly through the bone.
Bone compression and buckling: Anteroposterior bone compression causes the weakest part of the orbital wall to buckle, pushing out bone fragments.
Direct bone deformation: Unlike the hydraulic theory, direct impact to the eyeball is not necessarily required.
Both theories are considered valid based on cadaver studies. The mechanisms are thought to involve increased intraorbital pressure from external force causing fracture, and a contrecoup fracture where a distant point from the impact site fractures.
When the orbital wall is fractured and the orbit communicates with the paranasal sinuses, blowing the nose can force air into the orbit, causing orbital emphysema. This rapidly worsens periorbital swelling. Patients are instructed not to blow their nose for at least two weeks after injury.
A complete ophthalmic examination is essential. The first step is to rule out complications that threaten visual function, such as globe rupture or retinal detachment.
Orbital CT is mandatory for definitive diagnosis. Soft tissue window is useful for observing the positional relationship, displacement, herniation, incarceration, and strangulation of bone and soft tissues, while bone window is useful for detecting subtle fractures. Both windows should be ordered.
When orbital volume increases by 13% or more, the risk of enophthalmos is high. CT utilization rate was 88%, MRI 0.5% (UK survey). 4)
| Examination Method | Recommendation Level | Main Use |
|---|---|---|
| CT (soft tissue + bone window) | First choice | Fracture evaluation, incarceration confirmation, surgical planning |
| MRI | Adjunctive | Detailed soft tissue evaluation (after exclusion of metallic foreign bodies) |
| Plain X-ray | Not recommended | Fracture detection rate <50% |
After trauma, there may be intraocular metallic foreign bodies, and MRI is not the first choice due to safety concerns. CT is excellent for bone visualization and is most suitable for evaluating fractures, entrapment, and retrobulbar hemorrhage. MRI is used adjunctively when additional evaluation such as sinus mucocele is needed.
Treatment strategy is determined based on the fracture type and presence of entrapment, according to the following guidelines.
| Situation | Recommended Management | Rationale |
|---|---|---|
| Closed type with extraocular muscle entrapment | Emergency reduction surgery within 24 hours | Risk of muscle necrosis |
| Soft tissue entrapment (excluding muscle) | Surgery as early as possible (usually within 2 weeks) | Prevent tissue damage |
| Persistent oculocardiac reflex | Immediate surgery | Persistent vagal reflex |
| Open type / irreversible changes as main cause | Early reduction before scarring | Restore eye movement |
| Mild diplopia / reversible imaging changes | Observation | Spontaneous improvement expected |
In closed fractures with extraocular muscle entrapment, there is a risk of muscle necrosis, and emergency reduction surgery should be performed within 24 hours of injury. If orbital soft tissue other than muscle is entrapped, surgery should be performed as early as possible (usually within 2 weeks).
A UK survey found that 54% chose surgery 6–10 days after injury. 4) Surgical delay worsens prognosis. The residual enophthalmos rate is about 20% when repair is performed within 14 days, compared to about 72% when repair is performed after 6 months or more. 4)
Performed under general anesthesia. The orbital rim periosteum is approached percutaneously or transconjunctivally. After periosteal incision, the surgical field is developed posteriorly into the orbit. All prolapsed soft tissues are reduced into the orbit, displaced bone fragments are repositioned, and the defect is repaired with bone reconstruction materials. Damaged periosteum is sutured together or reconstructed with silicone or absorbable plates.
In a UK survey, approach selection was: subciliary 41%, infraorbital 37%, transconjunctival 7%. 4)
Open Approach
Indications: Combined medial wall and orbital floor fractures.
Incision: Subciliary or transconjunctival incision (for inferomedial wall), transcaruncular incision (for isolated medial wall fracture).
Advantages: Slight benefits in operative time, hospital stay, and cost.
Complications: Eyelid malposition, infraorbital nerve hypoesthesia. Subciliary incision carries a risk of cicatricial ectropion.
Endoscopic Approach
Procedure: Uncinate process resection → ethmoidectomy → identification of fracture site → reduction of herniated tissue → implant placement.
Advantages: Can be used for early repair, less globe traction. Suitable for medial wall and trapdoor fractures. Less soft tissue injury and hypoesthesia. 2)
Confirmation: Forced duction test and pulse test to verify eye movement and implant position.
Limitations: Not applicable for large defects.
The characteristics and complication rates of major reconstruction materials are shown below.
| Material | Characteristics | Material-related complication rate |
|---|---|---|
| Titanium mesh | Good rigidity and formability, suitable for large defects | 2.4% (741 cases)3) |
| Porous polyethylene (Medpor) | Fixed by tissue ingrowth, low infection rate | Not reported (326 cases)3) |
| Absorbable materials (Poly-L/D-lactic acid, PLLA) | Suitable for small to medium defects, low complications | 3.4% (176 cases)3) |
| Autologous bone (skull, iliac bone, etc.) | High biocompatibility but resorption is a concern | Donor site complications present3) |
| Silicone | Inexpensive, easy to handle | 17.5% (530 cases, highest value) 3) |
In a UK survey, 66% preferred silicone, but 66% of surgeons considered it inferior. 4) Reasons for implant removal were extrusion 70% and infection 46%. 4)
A systematic review of 444 cases reported that surgery improved enophthalmos in 85.2%, diplopia in 74.8%, eye movement restriction in 61.6%, and sensory disturbance in 61.1%. 2)
Surgery is not always necessary. Mild diplopia and movement disorders often improve spontaneously, and observation may be chosen. Closed fractures with extraocular muscle entrapment, persistent diplopia, or enophthalmos are main indications for surgery.
Two mechanisms have been proposed for orbital blowout fractures, both confirmed by cadaver studies: increased intraorbital pressure due to external force, and a contrecoup fracture at a site distant from the point of impact.
The cause of diplopia is not solely due to the fracture itself, but is considered to be multifactorial.
Orbital floor and medial wall fractures cause herniation of orbital contents into the paranasal sinuses. Expansion of the orbital volume leads to posterior displacement of the globe, resulting in enophthalmos. It is said that enophthalmos occurs when the orbital volume increases by 13% or more.
The medial orbital wall (lamina papyracea) is the thinnest of the orbital walls, and orbital fractures are classified as pure internal fractures (blow-out fractures) that by definition do not involve the orbital rim.
The use of custom-made implants based on CT images tailored to individual fracture patterns is advancing. Reduction in surgery time has been reported, with a significant reduction in the pre-contoured method (57.3±23.4 minutes) compared to the freehand contouring method (99.8±28.9 minutes). 2)
Endoscopic transnasal and transmaxillary approaches are associated with less soft tissue damage and less infraorbital nerve hypoesthesia compared to conventional percutaneous approaches. 2) They are considered particularly effective for medial wall fractures and trapdoor fractures, and wider adoption is expected.
In a narrative review of 66 studies and 3870 cases by Sivam & Enninghorst (2022), neobone formation was confirmed after complete absorption of Poly-L/D-lactic acid, and significant improvements in eye movement, diplopia, and enophthalmos were reported. 3)
A systematic review by de Santana et al. (2024) concluded that current evidence for a direct association between orbital floor fractures and ocular motility disorders is insufficient. 1) Further multicenter studies are needed to elucidate the pathophysiology.
