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Ocular System

Orbital floor fracture

“Blowout” fracture of the orbital floor is defined as a fracture of the orbital floor in which the inferior orbital rim is intact.

“Blowout” fracture of the orbital floor is defined as a fracture of the orbital floor in which the inferior orbital rim is intact.

  • Orbital floor fractures may occur in isolation (“blowout” fractures) or as part of a zygomaticomaxillary complex fracture.

Anatomy

  • Normal orbital volume ∼30 mL
  • Facial bones making up the bony orbit: Frontal, maxilla, zygoma, ethmoid, lacrimal, greater and lesser wings of the sphenoid, and palatine bones.
The orbital wall consists of frontal, ethmoid, lacrimal, maxilla, zygoma, sphenoid, and palatine bones. | Kim, H. S., & Jeong, E. C. (2016). Orbital Floor Fracture. Archives of craniofacial surgery, 17(3), 111–118. https://doi.org/10.7181/acfs.2016.17.3.111

Aetiology

  • Blunt trauma to the midface (M/C)

Pathophysiology

Bone-conduction theory:

A force, not powerful enough to fracture the rim, will propagate along the bone to fracture the weaker orbital floor (Le Fort).

Globe-to-Wall Theory:

When a force pushes the globe into the orbit and causes the globe to contact the orbital floor, resulting in a floor fracture.

Hydraulic mechanism:

Fracture is the result of increased intra-orbital pressure from the eye entering the orbit and not due to direct contact
Common fracture sites of blowout fracture of orbit (red line). Most thin portions of the orbit is medial to the infraorbital groove. | Kim, H. S., & Jeong, E. C. (2016). Orbital Floor Fracture. Archives of craniofacial surgery, 17(3), 111–118. https://doi.org/10.7181/acfs.2016.17.3.111

Clinical features

  • Diplopia (M/C complication)
  • Frank muscle entrapment:
    • Limited upward gaze
    • Vertical diplopia
  • Ocular movement restriction
  • Infraorbital nerve numbness
  • Reduced vision
  • Enophthalmos or hypoglobus (anatomic & volumetric changes of bony orbit affecting globe position)
Photographs of a patient with a left inferior orbital wall fracture showing restriction of both upgaze (A) and downgaze (B). | Grob, S., Yonkers, M., & Tao, J. (2017). Orbital Fracture Repair. Seminars in plastic surgery, 31(1), 31–39. https://doi.org/10.1055/s-0037-1598191

Diagnosis

Forced duction test:

Forced duction test should be performed to evaluate extraocular muscle entrapment. The examiner uses forceps to grasp the conjunctiva near the attachment of the inferior rectus muscle and attempts to move the globe through a full range of motion. Because of potential significant discomfort, this should be performed under sedation or anesthesia. | Kim, H. S., & Jeong, E. C. (2016). Orbital Floor Fracture. Archives of craniofacial surgery, 17(3), 111–118. https://doi.org/10.7181/acfs.2016.17.3.111

X-ray skull (Water’s view):

  • Hanging drop/teardrop sign: Orbital contents herniating through floor of orbit into maxillary antrum (CHARACTERISTIC)

Computed tomography (CT):

Ideal in the trauma setting to assess the orbit and to evaluate for cranial or other extraorbital injuries
Coronal computed tomography images of the obits showing a left inferior orbital wall fracture (A) and irregularity of the nasal globe contour of the left eye (B) suggesting a globe rupture. | Grob, S., Yonkers, M., & Tao, J. (2017). Orbital Fracture Repair. Seminars in plastic surgery, 31(1), 31–39. https://doi.org/10.1055/s-0037-1598191

Management

Orbital surgery:

  • Complications:
    • Infection of implanted material
    • Implant migration
    • Epiphora
    • Worsening diplopia
    • Lower-lid retraction
    • Blindness (d/t retrobulbar hemorrhage (RBH) or injury to the optic nerve)

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