Orbital fractures occur more commonly among young adult and adolescent males. In a retrospective series describing 92 adults with orbital fractures, the mean age was 32 years, and 72 percent were male. A retrospective series describing orbital fractures in children reported a mean age of 12.5 years. Of these children, 81 percent were boys.
The low prevalence of orbital fractures among younger children may be related to the following:
- The face of a child is relatively small compared with the head, and thus, most fractures in young children tend to involve the upper face and skull.
- In children, the proportion of cancellous to cortical bone is greater, providing more elasticity to the facial bones. In addition, sinus cavities are poorly developed. However, pneumatisation of the frontal sinus may actually be protective for adults with injury to the superior orbital rim.
- A prominent buccal fat pad affords some protection to the malar region of the face.
- Children are less likely to be exposed to occupational trauma, assaults, and major trauma associated with motor vehicle crashes.
Among adults with orbital fractures, the most frequent mechanisms of injury are assaults and motor vehicle collisions. For children, these injuries generally occur during sports or play.
Associated injuries — Orbital fractures are often the result of significant trauma and are frequently associated with other serious injuries including:
●Intracranial injury – Central nervous system (CNS) injury (eg, frontal cerebral contusion, epidural hematoma, subdural hematoma, and subarachnoid hemorrhage) may occur among patients with orbital fractures.
●Intraocular injury – Injury to the globe (such as ruptured globe, hyphema, or injury to the retina) can occur in association with an orbital fracture. In a case series describing adult patients with orbital fracture, 29 percent had a significant intraocular injury. In a retrospective series describing children with orbital fractures treated at a specialty hospital, 50 percent had associated eye injuries.
The orbit is formed primarily by five bones of the skull. Other nearby structures that must be considered when evaluating a patient with an orbital fracture include the:
- Extraocular muscles
- Medial and lateral canthal (palpebral) ligaments (which maintain the shape of the palpebral fissure)
- Lacrimal duct system
- Infraorbital and supraorbital nerves
The thick frontal bone forms the superior orbital rim and the roof of the orbit. The frontal sinus is adjacent to the superior medial portion of the roof of the orbit. The supraorbital nerve runs through the supraorbital notch, which is located at the junction of the medial and middle thirds of the superior orbital rim.
The greater wing of the sphenoid bone and the zygoma (which is relatively thick) form the lateral wall of the orbit. The lateral canthal ligament attaches to the zygoma.
The zygoma and the thin maxillary bone comprise the infraorbital rim and the floor of the orbit. The inferior oblique and inferior rectus muscles lie above the floor of the orbit. The maxillary sinus is beneath the orbital floor. The infraorbital nerve travels in a groove in the maxillary bone, further weakening it.
The maxillary and ethmoid bones form the medial wall of the orbit. The medial rectus muscle is adjacent to the medial wall, which overlies the ethmoid sinus. The medial canthal ligament attaches to the maxillary bone. The lacrimal duct system overlies the maxillary bone beneath the medial canthal ligament.
Three pairs of extraocular muscles move each eye in three directions: vertically (superior and inferior), horizontally (medial and lateral), and torsionally (intorsion when the eye rotates toward the patient’s nose and extorsion when the eye rotates toward the patient’s shoulder).
Fractures of the orbit may involve one or more of the walls of the orbit, the orbital rim, or both. Factors that influence the location and extent of the fracture include the mechanism of injury and the age of the patient. Injury to adjacent structures can also occur.
Orbital zygomatic fracture — The orbital zygomatic region is the most common location of a fracture of the orbital rim. This injury is typically the result of a high-impact blow to the lateral orbit. There is often an associated fracture of the orbital floor.
Nasoethmoid fracture — Fractures in the nasoethmoidal region of the medial orbital rim are also common. In a retrospective series of adult patients, 32 percent of fractures occurred in this area. Fracture of the maxillary bone in this portion of the orbital rim can result in disruption of the medial canthal ligament and the lacrimal duct system. In addition, the medial rectus muscle may become trapped in fractures of the medial wall of the orbit.
Orbital floor fracture — Fractures of the floor of the orbit, sometimes known as “blowout fractures,” typically occur when a small round object, such as a baseball, strikes the eye. Experimental evidence suggests that orbital floor fractures may be caused by one or both of the following mechanisms:
●Increased intraocular pressure as the result of posterior displacement of the globe (hydraulic theory)
●A direct blow to the infraorbital rim
In children, the floor of the orbit is more flexible. Consequently, it may fracture in a linear pattern creating a bone fragment that snaps back to create a “trap-door” fracture. In adults, the floor of the orbit is thinner and more likely to shatter when exposed to force.
A significant consequence of fractures of the orbital floor is entrapment of the inferior rectus muscle and/or orbital fat. Ischemia and subsequent loss of muscle function may occur either because of entrapment of muscle within the fracture fragment (more likely in children), or as the result of oedema and hemorrhage of muscle and extraocular fat that have prolapsed through the fracture into the maxillary sinus (more likely in adults).
Enophthalmos (the eye is receded into the orbit may develop when the globe is displaced posteriorly in association with an orbital floor fracture and prolapse of tissue into the maxillary sinus. Orbital dystopia (the eye on the affected side is lower in the horizontal plane than the other) may occur because entrapped muscle and orbital fat pull the eye downward.
Injury to the infraorbital nerve (resulting in decreased sensation along the cheek, upper lip, or upper gingiva) may occur as the result of an orbital floor fracture.
Orbital roof fracture — Orbital roof fractures are more common in younger patients (less than 10 years). This phenomenon is probably related to the high cranium-to-midface ratio of young children as compared with adults (thus exposing a larger upper surface for injury). In addition, pneumatisation of the frontal sinus helps the adult skull dissipate energy from forces to the superior orbital rim. As expected, orbital roof fractures have a high association with intracranial injury.
The initial priority for the management of patients with orbital fracture is to identify and treat life-threatening conditions.
Indications for surgical subspecialty consultation or referral — An ophthalmologist should be consulted during the initial evaluation in the following situations:
●Globe injuries (orbital or optic sheath hematoma, ruptured globe) – Emergency management of these injuries includes protection of the globe, elevation of the head, intravenous fluids as indicated for nausea and vomiting, and pain control. Patients with orbital hematomas may require an emergent lateral canthotomy to decompress the orbit. However, this definitive procedure should be performed by an ophthalmologist, whenever possible.
●Severe vagal symptoms (nausea, vomiting, bradycardia) associated with extraocular muscle entrapment – Severe vagal symptoms, in the absence of intracranial injury, may be caused by the oculocardiac reflex associated with extraocular muscle entrapment. These debilitating symptoms are usually relieved with release of the muscle. Preoperatively, ondansetron may be used for nausea and vomiting and atropine for symptomatic bradycardia.
As a specialist Professor Andi will further evaluate and look for:
●Muscle entrapment as the result of orbital floor or medial wall fractures.
●Enophthalmos or orbital dystopia that results in significant facial asymmetry.
●Naso-orbital-ethmoid fractures with injury to the medial canthal ligament and/or lacrimal apparatus.
Patients with orbital floor fractures who have persistent nausea and vomiting, eye muscle dysfunction, diplopia, enophthalmos, or orbital dystopia usually require surgery. Professor Andi prefers the scarless surgical transconjunctival approach for repairing orbital fractures.