Orbital Blowout Fracture: Which Ones Can Wait and Which Cannot

The orbital floor is designed to break. It gives way so that the pressure of a blow is dissipated downward instead of rupturing the globe.

An orbital blowout fracture is that protective mechanism doing its job – and then causing its own problems.

Orbital fat and muscle can herniate into the sinus below, the eye can sink backward, and eye movements can become restricted.

Most of these fractures do not need surgery, and many that look dramatic settle with time.

But one paediatric variant, in which a green-stick fracture traps the inferior rectus, is a surgical emergency measured in hours because the muscle is being strangled.

Knowing which fracture can wait, which needs planned repair, and which cannot wait at all is the core of managing orbital trauma.

What Is an Orbital Blowout Fracture?

An orbital blowout fracture is a fracture of the orbital walls – most often the floor or medial wall – caused by blunt trauma, with the orbital rim left intact.

The patterns that matter are:

Orbital floor fracture – the commonest, with herniation of orbital contents into the maxillary sinus
Medial wall fracture – through the thin lamina papyracea into the ethmoid sinus, often with orbital emphysema
Combined floor and medial wall fracture – larger defects with a higher risk of significant enophthalmos
Trapdoor (white-eyed) fracture – a paediatric green-stick fracture that springs shut and traps tissue, with minimal external signs
Orbital roof fracture – less common, more frequent in children, and associated with intracranial injury

The distinction between an adult comminuted floor fracture and a paediatric trapdoor fracture is the single most consequential one in this whole topic.

Epidemiology

Orbital fractures follow the epidemiology of facial trauma generally.

Assault, sports injury, falls and road traffic collisions account for the majority
Young adult men are disproportionately represented
The orbital floor and medial wall are the commonest sites because they are the thinnest orbital walls
Trapdoor fractures occur predominantly in children and adolescents, whose bone is more elastic and tends to hinge rather than shatter
Associated ocular injury is common enough that a full eye examination is mandatory in every case

A significant proportion of patients with an orbital fracture have a concurrent ocular injury, so the fracture must never be treated as the whole diagnosis.

Pathophysiology

Two mechanisms are described, and they are not mutually exclusive.

The hydraulic theory – a blow to the globe raises intraorbital pressure, which is transmitted to the walls and fractures the weakest point
The buckling theory – force applied to the orbital rim transmits a buckling wave through the floor, fracturing it without direct globe compression
Orbital fat, and sometimes the inferior rectus muscle, prolapses through the defect into the sinus below
Loss of orbital volume support and post-traumatic fat atrophy cause the globe to sink backward and downward – enophthalmos and hypoglobus
Entrapment or tethering of tissue restricts eye movement and produces diplopia
In trapdoor fractures the bone recoils and clamps the entrapped muscle, compromising its blood supply and causing ischaemia

Ischaemia is precisely why the trapdoor variant is urgent: this is a strangulated muscle, and the clock runs in hours rather than weeks.

Clinical Presentation

Symptoms

Periorbital swelling, bruising and pain following blunt trauma
Double vision, characteristically worse on upgaze with a floor fracture
Numbness of the cheek, upper lip, upper teeth and gum from infraorbital nerve injury
Orbital emphysema with crepitus, classically worse after nose-blowing in medial wall fractures
A sunken appearance of the eye, which often becomes apparent only as swelling settles
Nausea, vomiting and bradycardia – the oculocardiac reflex, a red flag for muscle entrapment

Examination Findings

$Orbital blowout fracture: coronal CT showing a left orbital floor fracture (arrowed) with orbital soft tissue herniating downward into the maxillary sinus$

Restricted eye movement, particularly limitation of upgaze, with diplopia in that direction
Enophthalmos measured by exophthalmometry, often masked initially by orbital swelling
Infraorbital hypoaesthesia mapped over the cheek and upper lip
Subcutaneous emphysema and crepitus on gentle palpation
A forced duction test to distinguish true mechanical restriction from a neurogenic palsy or pain-limited movement
Full ophthalmic assessment – visual acuity, pupils, intraocular pressure, and dilated fundus examination for hyphema, retinal dialysis, commotio retinae or globe rupture

In children, the absence of bruising is misleading rather than reassuring – the “white-eyed blowout fracture” describes a quiet-looking eye with a trapped muscle underneath.

Diagnostic Evaluation

Imaging

CT of the orbits with fine cuts in axial and coronal planes is the investigation of choice
Coronal images best demonstrate floor defects, herniated contents and the position of the inferior rectus
A rounded inferior rectus on coronal imaging suggests entrapment rather than simple prolapse
CT also identifies associated facial fractures and intraorbital foreign bodies

Ophthalmic Assessment

Complete examination to exclude concurrent globe injury, which changes management priorities entirely
Orthoptic assessment with formal measurement of the deviation and field of binocular single vision
Serial assessment as swelling resolves, since both diplopia and enophthalmos evolve over the first two weeks

Identifying the Emergency

A child or young adult with marked motility restriction, little swelling, pain on eye movement, and nausea or bradycardia
This combination should prompt immediate imaging and same-day surgical referral

The oculocardiac reflex in a young patient after orbital trauma is one of the few findings in ophthalmology that should move a patient straight to theatre.

Differential Diagnosis

Causes of restricted movement and diplopia after orbital trauma include:

Mechanical entrapment of the inferior rectus – positive forced duction test
Orbital haemorrhage and oedema causing restriction without entrapment – improves as swelling settles
Cranial nerve palsy from head injury – negative forced duction test
Direct extraocular muscle contusion
Orbital compartment syndrome with retrobulbar haemorrhage – a separate sight-threatening emergency requiring immediate canthotomy and cantholysis
Globe rupture, which must be excluded before any forced duction testing is attempted

Forced duction testing is contraindicated until globe rupture has been excluded, since manipulating a ruptured eye can expel intraocular contents.

Management

Immediate Care

Advise against nose-blowing, which forces air into the orbit and can cause dramatic emphysema or even orbital compartment syndrome
Ice packs and head elevation to limit swelling
Antibiotic cover is often given where the fracture communicates with a sinus, though practice varies
A short course of oral corticosteroids is sometimes used to reduce oedema and clarify the true extent of restriction

Immediate Surgery

Trapdoor fracture with muscle entrapment, particularly in children, ideally within 24 to 48 hours to prevent permanent muscle ischaemia and fibrosis
Associated oculocardiac reflex with bradycardia, nausea and vomiting

Planned or Deferred Repair

Repair is commonly considered within roughly two weeks for persistent symptomatic diplopia in functional gaze positions, significant enophthalmos, or a large floor defect likely to produce late enophthalmos
Surgery involves releasing herniated tissue and reconstructing the floor with an implant
Many small fractures with resolving diplopia and no significant enophthalmos are managed conservatively with observation
Delayed repair is more difficult once scarring has occurred, which is why the two-week window matters

The practical rule is that most adult fractures can be observed for a fortnight while swelling settles, but a child with a trapped muscle cannot wait even a day.

Prognosis

Most patients do well, and the outlook is best when the urgent cases are identified early.

Diplopia from swelling and haemorrhage usually resolves over days to weeks without surgery
Trapdoor fractures released promptly generally recover full motility; delayed release risks permanent restriction from muscle fibrosis
Infraorbital numbness improves in many patients over months, but can be permanent
Enophthalmos may become apparent only after swelling resolves, and is harder to correct once late
Persistent diplopia in primary or reading position after adequate repair may require prisms or strabismus surgery

Because both diplopia and enophthalmos declare themselves as swelling settles, review at one to two weeks is what turns an initial assessment into a reliable one.

References

Burnstine MA. Clinical recommendations for repair of isolated orbital floor fractures: an evidence-based analysis. Ophthalmology. 2002.
Jordan DR, Allen LH, White J, et al. Intervention within days for some orbital floor fractures: the white-eyed blowout. Ophthalmic Plastic and Reconstructive Surgery. 1998.
Boyette JR, Pemberton JD, Bonilla-Velez J. Management of orbital fractures: challenges and solutions. Clinical Ophthalmology. 2015.
Orbital Floor Fracture. StatPearls, NCBI Bookshelf.
Orbital Fractures. EyeWiki, American Academy of Ophthalmology.