Orbital Fractures

Anatomy

The orbit is a pyramidal structure with the apex located posteriorly and the base anteriorly. It is comprised of 7 bones:
• Frontal bone
• Zygomatic bone
• Maxilla
• Sphenoid
• Ethmoid
• Palatine
• Lacrimal
With regards to trauma, it is important to be aware of the borders:
• Roof – frontal bone and lesser wing of the sphenoid
• Medial wall – ethmoid, maxilla, lacrimal and sphenoid bones
• Lateral wall – Zygoma and greater wing of sphenoid
• Floor – maxilla, palatine and zygomatic bone
With regards to the extraocular muscles, there are 6 muscles which move the globe. This is relevant with orbital fractures.

Signs and symptoms of an orbital fracture

• Peri-orbital ecchymosis
• Diplopia
• Restriction in eye movements typically with upward gaze
• Enophthalmos/exophthalmos
• Hypoglobus
• Numbness in V1/V2 distribution
• Surgical emphysema of surrounding tissues
• Abnormal pupillary reflex
• Subconjunctival haemorrhage
• Change in visual acuity

Special Investigations

CT scans are the imaging modality of choice for orbital fractures. It is recommended to obtain a CT head as there are occasionally concomitant facial fractures. Ensure you have all 3 views of the CT available – coronal, axial and sagittal. Thing to look for include disruption of the bony orbital floor and herniation of the orbital contents. It's also important to rule out haematoma within the orbit. Orbital floor fractures can be seen on OM views classically demonstrated as a tear drop sign.

Management

Your acute management for orbital fractures are to advise the patient to avoid blowing their nose, sleeping with the head of bed elevated and using cold compresses to reduce periorbital oedema. If there are any concerns regarding the eye (as concomitant eye injury is common) involve the ophthalmologists early.
Timing of when to manage an orbital floor fracture surgically can be controversial. A decision is required in terms of whether to monitor a fracture or surgically intervene and this decision is dependent on clinical findings, CT scan as well as the benefits and risks of surgery, dependent on local opinion and protocol. This will often be a consultant decision. Generally your window for surgical intervention is 14-21 days from the date of the fracture if it is going to be managed acutely. This however is not the case in children due to the risk of long term complicaitons. All suspected and confirmed orbital fractures should be discussed with a senior as soon as possible
The majority of orbital fractures are managed conservatively. Even if surgical intervention may be required, the decision may not be made until the patient is reviewed post-operatively at 1 week. This allows for resolution of swelling and bruising so a more accurate assessment of the fracture and functional/cosmetic complications. Diplopia while concerning is common with orbital fractures however it commonly resolves 7-14 days post-fracture [5].
General indications for surgical intervention:
• Enophthalmos > 2mm
• Ocular motility dysfunction
• Persistent diplopia
• Poor aesthetics
• Large fractures with significant displacement (hypoglobus)
• Orbital blowout fracture with entrapment
• Retrobulbar haemorrhage

With surgical procedures there is a risk of blindness (due to retrobulblar haemorrhage) from these operations as well as other eye signs such as enophthalmos, diplopia, traumatic optic neuropathy, superior orbital fissure syndrome. Therefore, the patient should follow strict eye observation protocols in line with your trust protocol when they return to the ward post-operatively. For example:
• Every 15 minutes for 2 hours
• Every 30 minutes for 2 hours
• 1 hourly for 16 hours
In terms of what these eye observations comprise:
• Visual acuity
• Reaction to light
• Retrobulbar pain
• Proptosis
• Diplopia
If there are any concerns arising from the eye observations, this should be raised with the registrar. Irrespective of conservative/surgical management, these patients should always be followed up on an outpatient basis. If patients are managed conservatively they are frequently reviewed at 3 months where late onset complications can be assessed. Operative intervention can be pursued however can be more surgically challenging.

Retrobulbar Haemorrhage (RBH)

This is an uncommon, rapidly progressing emergency which can result in loss of vision. There is an accumulation of blood in the retrobulbar space which results in an increase in intra-ocular pressure which can damage the neurovascular bundle. For OMFS clinicians we are likely to see RBH in patients who have had orbital surgery or complex facial fractures involving the ZMC or the orbit.

Signs and Symptoms

Includes but not limited to:
• Severe orbital pain
• Ophthalmoplegia
• Proptosis
• Subconjunctival haemorrhage
• Nausea, vomiting
• Loss of red vision
• Fixed and dilated pupil
• Tense globe (due to increased IOP)

Surgical intervention is required ASAP as this is a sight threatening condition. A lateral canthotomy is required to decompress the orbit and relieve the increased intraocular pressure. To prevent permanent damage, surgical intervention should ideally be carried out within 2 hours. Further decompression may be required and this can be done via inferior cantholysis and surgical evacuation of the orbit if a persistent haematoma is present.
Once surgical intervention has been successful, the patient should be monitored with regular eye observations.
It is important to mention that performing a lateral canthotomy is likely outside the skill set of an SHO therefore if you suspect a retrobulbar haemorrhage, call your registrar and the on-call ophthalmologist immediately.

Trapdoor Fracture

A separate section has been dedicated for orbital floor fractures in the paedatric population. An orbital floor/blowout fracture in children is referred to as a trapdoor fracture. In children this requires immediate surgical intervention as it can lead to visual impairment. These fractures are referred to as trapdoor because in adults a blowout fracture leads to downwards displacement of the orbital floor. This is akin to a door opening and remaining open meaning there is herniation of the orbital contents but without entrapment. In contrast, the bones of a child are more elastic and therefore a blowout fracture in children will result in herniation of the orbital contents but due to the “elasticity” of the orbital floor, entrapment of orbital contents and the inferior rectus occurs as the floor returns back to a more normal position.

White eye blowout as it can be called generally has similar signs and symptoms to those in adults (mentioned above) however there are some stark and highly unique differences. It is referred to as a white blowout fracture due to the absence of traumatic findings (no subconjunctival haemorrhage) but restriction of upwards gaze and a general feeling of malaise. Another unique feature of this injury in children is stimulation of the oculocardiac reflex. There is an increase in ocular pressure which is results parasympathetic stimulation of the heart and gut via the vagus nerve. Clinically this will present as nausea, vomiting and bradycardia.[8]
If you suspect a trapdoor fracture in a child, call your registrar and the on-call ophthalmologist as surgical intervention is required immediately.

References