3.3 Orbital Fractures Flashcards
What are the most common causes of orbital fractures?
- Orbital fractures are the most common facial fractures.
o Blunt trauma
o Most common causes:
Assult
RTA
Fall
What are the most common types of orbital fractures?
- Orbital floor fractures
- Medial wall fractures
- Inferior medial wall fractures
What are the classifications of orbital trauma (Converse and Smith classification)?
a. Pure (blow in or blow out fractures) – fracture of the internal walls with intact rims
b. Impure (complex with involvement of one or more rimes) – assocaited fractures of the rims
What are the three biomechanical theories of orbital trauma?
- The globe to wall theory (or hydraulic theory)
- Retropulsion theory
- Buckling theory
What is the globe to wall (hydraulic) theory?
Posterior displacement of the globe after a direct hit transmits forces along the walls resulting in fracture of the thinner walls (Pfeiffer, 1943).
What is the retropulsion theory?
Sudden increase in intra-orbital pressure caused by a direct hit from a large object creates stresses along the orbital walls resulting in fractures at the areas of least thickness (King, 1944).
What is the Buckling theory?
A ripple effect created in the floor from a direct hit. The ripple thus created causes compression in an anteroposterior direction and resultant fracture at the posteromedial part of the orbital floor commonly.
What are some key orthoptic assessments required for orbital fractures?
- Hess Chart
- Fields of BSV
- Uniocular fields of fixation
What are some limitations in testing patients with orbital fractures?
- Early swelling
- Pain
- Mild restrictions may be missed on Hess chart
- Subjective responses
- Combination of all tests needed to formulate a diagnosis, never interpret one test in isolation.
What conditions are needed to immediately intervene in orbital fractures? (within 24hrs)
o “white eye” blow out
o CT evidenced entrapment with positive FDT & oculo-vagal response
o Vision threatening emergency
What conditions are needed to ‘early’ intervene in orbital fractures? (within 14 days)
o CT evidenced entrapment with positiove FDT & non resolving diplopia
o Early onset enophthalmos/hypopthalmos
o >50% or >2x2cm floor defect
What conditions are needed to ‘late’ intervene in orbital fractures? (over 14 days)
o Non-resolving symptoms
o Late enophthalmos/hypopthalmos
Which surgical technique is good for medial wall repair?
Trans-caruncular
Name three surgical techniques used in orbital fractures
Trans-conjunctival approach
Trans-caruncular
Lateral Canthotomy
What materials may be used in ocular implants?
o Titanium
o Bone graft
o Porous polyethylene
o Composite porous polyethylene
o Resourbable (PLLA)
o Pre-formed anatomical implant – 3D
What are the aims of surgery in orbital fractures?
- To release entrapped tissue
- Motility
- Appearance exophthalmos/enophthalmos/hypoglobus/hyperglobus
What are some early post op considerations when dealing with orbital fractures?
o Ensure no signs of orbital compartment syndrome
o Trap door cases – motility recovery slow
What are some mid-late post op considerations when dealing with orbital fractures?
o Motility may worsen in PP – pt more symptomatic
May need strab surgery 6-12m post orbital surgery
o Treating cases with severe enophthalmos motility may worsen
Name three other mechanical disorders
- Strabismus fixus
- Adherence syndrome
- Muscle pulley abnormalities
What does strabismus fixus look like?
- V. large angle esotropia with bilateral abduction deficit
- +/- high myopia – heavy eye syndrome
Name some causes of strabismus fixus
- Congenital – believed to be caused by fibrosis which explains loss of elasticity of medical rectus
- Longstanding lateral rectus palsy – causes secondary contracture and fibrosis of medial rectis
- Myopia – patients with high myopia have a weak intermuscular septa especially between superior rectus and medial rectus and lateral rectus and inferior rectus. This causes the superiror rectus to slip medially towards the medial rectus and lateral rectus to slip inferiorly, thus fixing the eye medially and down (esotropia and hypotropia) – AKA heavy eye syndrome.
- Amyloidosis – Infiltration of EOM by amyloid causes loss of elasticity of the EOM.
- Unspecific – progressive fibrosis, myopathy and myositits is thought to be the cause of strabismus fixus occuring in convergent form.
What are some differentials of strabismus fixus?
o New onset bilateral 6th
o Congenital bilateral 6th – difficult to differentiate
o Imaging required to help rule out SOL (superior oblique lesion?), raised ICP
Muscle slippage
o FDT
How is strabismus fixus managed?
o Convergent form of strabismus fixus no high myopia
Disinsertion of MR and LR resection with recession of conjunctiva and tenons – compromise of abduction
o Myopic strabismus fixus (heavy eye syndrome)
Loop myopexy – unites the lateral and superior rectus muscles with non-absorbable suture 15mm behind the limbus.
+/- MR muscle recession in cases of contracture. Disadvantage of suture myopexy includes muscle strangulation, which may affect anterior ciliary circulation and may rarely cause cheese-wiring of the muscle.
How does adherence syndrome present?
o Fat adherence syndrome – progressive hypotropia of the affected eye, limitation of the elevation (specifically in abduction) and an upper lid retraction
What causes adherence syndrome?
- Fusion of the facial sheaths
What are the three different types of adherence syndrome?
o Congenital – defective cleavage of the mesoderm where EOMs are not differentiated from each other
o Acquired – trauma, inflammation, or surgery
o Most common form may be fat adherence syndrome – caused by disruption of the orbital fat during the inferior oblique muscle or scleral buckling surgery.
How is adherence syndrome usually managed?
Surgically
What are the developmental disorders of pulley position?
o Craniosynotosis – results in either incyclo or excyclotorsion of the entire orbit
o Incyclotorsion
Right orbit – displaced clockwise
Left orbit – counter clockwise
Resulting in A patterns in EOMs
o Exyclotorsion
Right orbit – counter clockwise
Left orbit – clockwise
Resulting in V pattern EOMs
What are the acquired disorders of pulley position?
o Connective tissue disorders
Marfans and Ehlers-Danlos syndrome – weaken the strength and rigidity of collagen might lead to unstable pulleys
o Heavy eye syndrome – Myopic strabismus fixus
o Traumatic pulley disorders – Trauma: orbital fracture or iatrogenic
o Senile degeneration pulley disorders – myopic distance. Slippage of the LR inferiorly, losing its abduction force.
How are muscle pulley abnormalities best managed?
Surgery
