From the Guidelines
Fractures to the orbital floor affect vertical gaze because they can physically entrap the inferior rectus muscle, which is responsible for downward eye movement, thereby restricting the normal movement of the eye, particularly during upward gaze. When this muscle becomes trapped in the fracture site, it restricts the normal movement of the eye, particularly during upward gaze. The inferior rectus muscle normally relaxes during upward gaze to allow the superior rectus to elevate the eye. When trapped, the muscle cannot elongate properly, mechanically limiting the eye's ability to look upward. This entrapment creates a tethering effect, preventing the normal excursion of the eyeball. Patients typically experience vertical diplopia (double vision) specifically when attempting to look upward because the affected eye cannot move in synchrony with the unaffected eye. The restriction is mechanical rather than neurological, which is why forced duction testing often reveals limited movement. Additionally, swelling and hemorrhage around the fracture site can further exacerbate the restriction of eye movement. This condition requires prompt evaluation, as prolonged entrapment can lead to muscle ischemia and permanent dysfunction, as indicated by the most recent guidelines 1.
Key Points to Consider
- The inferior rectus muscle plays a crucial role in downward eye movement, and its entrapment can significantly impact vertical gaze.
- The entrapment of the inferior rectus muscle in an orbital floor fracture can lead to mechanical restriction of eye movement, resulting in vertical diplopia.
- Prompt evaluation and management are essential to prevent long-term complications such as muscle ischemia and permanent dysfunction, with guidelines suggesting repair within specific timeframes based on the presence of symptoms and the extent of the fracture 1.
- Surgical intervention, including recession of the restricted muscles, may be necessary to correct the misalignment and improve binocular vision, with the goal of eliminating diplopia in primary position and downgaze 1.
Management Considerations
- The timing of surgical repair is critical, with immediate repair indicated for patients with CT evidence of an entrapped muscle or periorbital tissue associated with a nonresolving oculocardiac reflex, and repair within 2 weeks for symptomatic diplopia with positive forced ductions or entrapment on CT and minimal improvement over time 1.
- The use of forced duction testing and other diagnostic tools can help determine the extent of the restriction and guide surgical planning, as emphasized in recent studies 1.
- Postoperative care and follow-up are essential to monitor for potential complications and adjust treatment as needed, considering the complexity of managing vertical deviations in orbital floor fractures 1.
From the Research
Mechanism of Vertical Gaze Impairment
- Fractures to the orbital floor can entrap the inferior rectus muscle, leading to impairment of vertical gaze [(2,3,4,5)].
- The entrapment of the inferior rectus muscle can cause vertical diplopia on upward gaze and restriction of upward eye movement [(2,5)].
- The severity of the trauma and the extent of muscle damage can affect the outcome and the development of sequelae 6.
Clinical Presentation
- Patients with orbital floor fractures may present with vertical diplopia, limited upward gaze, and normal visual acuity [(2,5)].
- Orthoptic assessment may show hypertropia and exotropia in primary position 2.
- Imaging studies, such as CT and MRI, can help diagnose muscle avulsion and entrapment [(2,6)].
Management and Treatment
- Surgical repair of the orbital floor fracture and release of the entrapped muscle can improve symptoms [(3,5)].
- Extraocular muscle surgery, such as recession or resection of the inferior rectus muscle, may be necessary to restore binocular single vision [(3,4)].
- Early surgical repair within 7 days of injury can result in more rapid improvement of ductions and diplopia 5.