Isolated Orbital Fractures – Review Flashcards

These flashcards cover definitions, anatomy, classifications, mechanisms, clinical assessment, imaging, surgical indications, approaches, materials and complications related to isolated orbital fractures.

What makes orbital fractures unique among cranio-maxillofacial injuries?

They have functional, cosmetic and psychological implications, directly threaten vision, and are among the few true emergencies in CMF trauma.

How many bones form each bony orbit and what are they?

Seven – maxilla, frontal, zygomatic, sphenoid, ethmoid, lacrimal and palatine bones.

Which three bones form the orbital rims?

Maxilla (inferior rim), zygomatic bone (lateral rim) and frontal bone (superior rim).

Describe the general shape and orientation of the orbital cavity.

A pyramidal structure with a quadrilateral base (orbital aperture) anteriorly and an apex superomedially placed posteriorly at the optic foramen.

Name the two major fissures found within the orbit.

1. Superior orbital fissure (inter-sphenoidal) 2. Inferior orbital fissure (spheno-zygomatic).

List five major structures that occupy the orbit.

Eye/globe, optic nerve, extra-ocular muscles, ophthalmic vessels, orbital fat (others include cranial nerves III, IV, VI and trigeminal branches V1/V2, ciliary ganglion, nasolacrimal apparatus).

Give four common causes (aetiology) of orbital fractures.

Physical assault, sports injuries, motor-vehicle accidents, falls (also industrial accidents, projectile injuries).

According to Manson et al., what are the three energy-based types of orbital fractures?

a) Trap-door (low-velocity) b) Medial blowout (intermediate-velocity) c) Lateral blowout (high-velocity).

How did Converse and Smith classify orbital fractures?

Pure (internal wall fracture with intact rims – blow-in/out) versus Impure (complex fractures involving one or more orbital rims).

Differentiate blow-out and blow-in orbital fractures.

Blow-out: outward displacement of internal wall, may entrap periorbital tissue causing enophthalmos. Blow-in: inwardly displaced fragment reduces intra-orbital volume, often causing proptosis.

What are Hammer’s four classes of orbital fractures?

Type I Orbito-zygomatic, Type II Internal orbital (isolated wall/roof/floor), Type III Naso-orbito-ethmoid, Type IV Complex facial fractures involving the orbit.

State the three main theories explaining orbital blow-out fracture mechanism.

1. Globe-to-wall (hydraulic) theory 2. Retropulsion theory 3. Buckling (transmission) theory.

In the 8-point ophthalmic examination, what are the first three assessments?

1) Visual acuity & fields 2) Pupillary examination 3) Extra-ocular motility & alignment.

Name five common clinical signs of orbital fracture.

Periorbital oedema/ecchymosis, subconjunctival haemorrhage, diplopia, subcutaneous emphysema with crepitus, enophthalmos (others: hypoglobus, step deformity, infra-orbital nerve hypoaesthesia).

Define enophthalmos, proptosis and hypophthalmos.

Enophthalmos – posterior displacement of globe. Proptosis (exophthalmos) – anterior displacement. Hypophthalmos (hypoglobus) – downward displacement of globe due to orbital floor defect.

How do you distinguish hypophthalmos from orbital dystopia?

Hypophthalmos: only the globe is displaced downward; orbital dystopia: entire bony orbit and its contents are displaced.

Differentiate monocular and binocular diplopia post-trauma.

Monocular diplopia persists when the fellow eye is closed (usually ocular media pathology). Binocular diplopia appears only with both eyes open and is most commonly due to orbital edema, muscle entrapment or neurogenic injury.

What is the oculocardiac (trigemino-cardiac) reflex and its key symptoms?

Afferent trigeminal ophthalmic fibers trigger vagal efferents causing bradycardia, hypotension, nausea, vomiting, malaise – can be life-threatening.

List two syndromes associated with severe orbital apex injuries.

1) Superior orbital fissure syndrome 2) Orbital apex syndrome (includes all features of the former plus partial/total vision loss).

What classic radiographic sign suggests an orbital blow-out fracture on an occipitomental view?

The ‘teardrop sign’ – a polypoid mass of herniated orbital contents hanging into the maxillary sinus.

Give one indication each for immediate, early and late orbital fracture surgery.

Immediate (

What is a ‘white-eye’ blow-out fracture?

A paediatric trap-door fracture with minimal external bruising but muscle entrapment causing severe motility restriction and oculovagal symptoms.

Name two relative contraindications to orbital fracture repair.

1) Severe associated ocular injuries (e.g., ruptured globe, retinal tear). 2) Only seeing eye involved when the contralateral eye is blind.

List four surgical approaches to the orbit.

Transcutaneous (medial/lateral), Trans-caruncular, Trans-conjunctival (inferior fornix), Trans-antral endoscopic-assisted (others: coronal).

Give two advantages and one disadvantage of the transconjunctival approach.

Advantages: excellent cosmesis, minimal ectropion, wide 270° access without skin incision. Disadvantage: medial extension limited by lacrimal drainage system.

Why are isolated orbital roof fractures clinically significant?

They may be associated with dural tears, CSF leak, intracranial fragment displacement, tension pneumocephalus or frontal‐lobe contusion.

State three factors that may necessitate surgical management of orbital roof fractures.

Presence of CSF leak, need to retrieve intracranial bone fragments, ophthalmic signs compromising vision or large displaced fragments altering orbital volume.

How can unrepaired lateral wall fractures affect globe position?

They increase internal orbital volume and can lead to enophthalmos; reconstruction or augmentation restores volume and corrects globe position.

Which orbital walls are thinnest and most likely to fracture?

The medial wall and the floor of the orbit.

Which extra-ocular muscle is most commonly entrapped after orbital trauma and how soon should it be released?

Inferior rectus (followed by medial rectus); must be released within 24–48 hours to avoid irreversible ischemic contracture.

What are the three main indications for surgical repair of medial wall/floor fractures?

1) Restriction of ocular motility 2) Diplopia 3) Clinically significant enophthalmos.

Summarise Nolasco’s CT-based classification of medial wall fractures.

Type I isolated medial wall; Type II medial wall + floor; Type III medial wall + floor + zygomatic complex; Type IV medial wall + other complex facial fractures.

List three materials commonly used for orbital wall reconstruction.

Titanium meshes/plates, porous polyethylene sheets (Medpor), autogenous bone grafts (e.g., calvarial or iliac).

Name four possible complications following orbital fracture surgery.

Prolonged chemosis, orbital fat prolapse, eyelid retraction, persistent diplopia (others: canalicular injury, symblepharon, scarring).

Why is a multidisciplinary approach important in managing orbital fractures?

Because of the orbit’s complex anatomy and its relationship to vision, combining expertise (OMFS, ophthalmology, neurosurgery, ENT) optimises functional and aesthetic outcomes.