Orbital floor fractures
Blunt facial trauma is the usual cause of orbital floor fractures. The term blowout fracture is used when the rim remains intact. Orbital floor fracture is thought to be due to either of the following: an acute increase in intraorbital pressure, which occurs when a direct impact occludes the orbital entrance; or compression of the rim, which results in buckling of the floor. Orbital floor fracture can be part of more extensive fractures of the orbit and midface. In some cases, the mechanism causing floor fractures extends to include the medial wall as well.
Periorbital ecchymosis and diplopia are common in the immediate posttrauma period. Injury to the inferior rectus muscle or to its nerve, with resultant weakness, may be caused by hemorrhage or ischemia, in addition to restriction. This injury can occur either at the time of the fracture or during its repair. Injury to the inferior rectus muscle can manifest as either limited elevation or depression. Hypoesthesia in the cutaneous distribution of the infraorbital nerve can also occur.
In a patient with limited elevation, a positive forced duction test indicates the presence of restriction. Bradycardia, heart block, nausea, or syncope can occur as a vagal response to entrapment. When the entrapment involves the more anterior portion of the orbital floor or when there is associated injury to the inferior rectus muscle or its nerve, there can also be limited depression. Reduced saccadic velocity and force generation on attempted downgaze suggest weak muscle action. Orbital computed tomography and high-resolution, multipositional magnetic resonance imaging are useful for revealing the presence and extent of the injury.
A special presentation, the white-eyed blowout fracture, is characterized by marked restriction (in both directions) of vertical ocular motility despite minimal signs of soft-tissue injury. This restriction is due to entrapment of the inferior rectus muscle or orbital tissue either beneath a trapdoor fracture or, unique to children, in a linear opening caused by flexion deformity of the floor. In this condition, early surgery, rather than observation, is required in order to minimize permanent muscle and nerve damage.
There are several approaches to the management of orbital floor fractures. Some clinicians advocate surgical exploration in all cases, irrespective of the results of forced duction testing. The justification for this approach is that, especially with large bony defects, progressive herniation of orbital contents into the adjacent maxillary sinus can occur, resulting in disfiguring enophthalmos. Others recommend waiting for a few days to 2 weeks to allow periorbital ecchymosis to subside. For these surgeons, the main indication to operate is evidence of restriction with unresolved diplopia in primary position. Diplopia immediately after the injury is common and is not necessarily an indication for urgent intervention. Management of persistent diplopia is covered in Chapter 11.
Orbital roof fractures
Though rare in older patients, orbital roof fractures are common in children younger than 10 years. Isolated roof fractures typically result from impact to the brow region in a fall, often from a height of only a few feet. The principal external manifestation is upper eyelid hematoma (Fig 27-3). These fractures often heal without treatment.
For further discussion of diagnosis and management of orbital trauma, see BCSC Section 7, Oculofacial Plastic and Orbital Surgery.
Figure 27-3 Orbital roof fracture in a child, resulting from direct impact to the brow region in a fall. A, Marked right upper eyelid swelling from a hematoma originating in the superior orbit, adjacent to a linear fracture. B, Coronal computed tomography shows a bone fragment displaced into the right orbit.
Excerpted from BCSC 2020-2021 series: Section 10 - Glaucoma. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.