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The Role of the Dentist in Recognizing Orbital and Ocular Trauma


June 4, 2018
by Matthew D. Morrison, DMD, MD, MSc; Henry J. Lapointe, DDS, PhD, FRCD(C); Jerrald E. Armstrong, BSc, DDS, MSc, FRCD(C)

Introduction
General dentists and dental specialists alike are often called upon by Emergency Department (ED) physicians to assess patients with dental injuries and concomitant maxillofacial trauma. Whether the assessment occurs in the ED, the hospital ward, or the private dental clinic, a full examination of the oral and maxillofacial structures is required to identify all facial injuries. While a computed tomography (CT) scan helps to visualize even the most inconspicuous of facial fractures, a thorough head and neck examination will often reveal such injuries before imaging has been performed. Of particular importance are fractures of the orbit, where delicate nerves and muscles may become entrapped between bone fragments, or compressed by hematoma or edema, leading to ischemia and potentially permanent disability. Timely, evidence-based management of orbital and ocular trauma will prevent many, if not all, long-term disabilities and/or deformities.
Described herein are cases of orbital trauma referred to, and managed by, the Oral and Maxillofacial (OMF) Surgery service at London Health Sciences Centre in London, Ontario, Canada.

Case Presentation
A healthy 56-year-old man was referred to the OMF Surgery service for assessment and management of a left-sided orbital floor fracture. The patient was involved in an altercation four days prior, during which he received a blow directly to the left eye. Due to persistent pain and double vision (diplopia) on upward gaze in the affected eye, the patient sought medical attention. On presentation to the ED, the patient was awake, alert, and oriented to person, place, and time. All vital signs were stable and the patient was afebrile. Head and neck examination revealed left-sided periorbital ecchymosis and subconjunctival hemorrhage (Fig. 1A). Palpation of the facial bones revealed no overt step deformities or point tenderness. There was mild binocular diplopia on upward gaze, but there was no diplopia in primary gaze, monocular diplopia, or ophthalmoplegia (impaired extraocular movements). No enophthalmos (anteroposterior retrusion of the globe) could be appreciated but there was mild hypoglobus (vertical depression of the globe). No lagophthalmos (inability to completely close the eyelids), proptosis (anteroposterior protrusion of the globe), or severe pain in the left eye was detected. The pupils were round, briskly reactive, and measured 3-mm bilaterally. There was no relative afferent pupillary defect (RAPD), which suggested preservation of the autonomic innervation of the eye (i.e., parasympathetic nerves traveling along cranial nerve [CN] III, and sympathetic nerves traveling along the ophthalmic nerve [V1 distribution of CN V]). The patient’s visual acuity–while wearing his glasses–was 20/20 in the right eye (ocular dextra [OD]) and 20/30 in the left eye (ocular sinistra [OS]), which was consistent with his baseline. Visual fields were normal. There was mild hypoesthesia of the infraorbital nerve (i.e., the V2 distribution of CN V), but no other CN deficits were detected. Intraoral examination revealed no other injuries, and the occlusion was unaltered. The remaining maxillofacial, cervical spine, cardiovascular, respiratory, and abdominal examinations were normal.

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CT imaging revealed an isolated left-sided orbital floor defect with herniation of the intraorbital soft tissues (i.e., periorbita, fat, inferior rectus muscle, and infraorbital neurovascular bundle) into the maxillary sinus (Figs. 1B & 1C). The orbital apex and orbital fissures were intact, and there was no retrobulbar hematoma. This patient was diagnosed with an isolated left orbital “blow out” fracture.

Fig. 1A, B, C
A, Clinical photograph demonstrating left-sided periorbital ecchymosis and subconjunctival hemorrhage. CT scan showing isolated left-sided orbital floor fracture in coronal (B), and sagittal (C) views.

The risks and benefits of surgical reconstruction of the orbital floor versus observation for resolution of pain and diplopia were discussed with the patient. Of note, the mild enophthalmos at four days post-injury was likely to worsen once the swelling had resolved, and the patient preferred timely surgical correction of his injury. The surgical treatment plan was consented to, and the patient thus underwent open reduction and internal fixation (ORIF) of his left orbital floor fracture under general anesthesia. To reconstruct the orbital floor, a titanium mesh prosthesis (KLS 1.5-mm Micro Orbital Mesh, Jacksonville, FL, USA) was anatomically contoured, inserted, and fixated with titanium screws (Figs. 2A-2C). The surgical approach to the orbit was a transconjunctival incision with lateral cathotomy (i.e., a short skin incision at the lateral canthus) and inferior cantholysis (i.e., release of the inferior limb of the lateral canthal tendon).

A postoperative CT scan revealed ideal anatomical reduction of the orbital contents and reconstruction of the orbital floor anatomy (Figs. 3A & 3B). At three months postoperatively, the patient had no complaints other than mild residual diplopia, which had been gradually resolving (Fig. 3C). The slight vertical overcorrection of the globe had been progressively settling down as the periorbital soft tissues remodeled. Postoperative ophthalmological consultation confirmed that resolution was expected without further intervention.

Fig. 2A, B, C
A, Transconjunctival incision with lateral canthotomy and inferior cantholysis followed by dissection down to periosteum at the infraorbital rim. B, Titanium mesh prosthesis (KLS 1.5-mm Micro Orbital Mesh, Jacksonville, FL, USA). C, Insertion of the titanium mesh prosthesis and titanium screws to reconstruct the orbital floor.

Fig. 3A, B, C
Postoperative CT scan showing reconstruction of the left orbital floor in coronal (A) and sagittal (B) views. C, Clinical photograph showing slight residual vertical overcorrection of the left globe at three months postoperatively.

Discussion
Physical altercations, falls, sporting accidents, occupational accidents, and motor vehicle accidents (MVAs) are frequent causes of dentoalveolar injuries and/or maxillofacial trauma. Patients with injuries limited to the non-tooth-bearing facial skeleton have been found to have associated dental trauma in 10% of cases. 1 Concomitant dental injuries are more frequent with isolated mandibular fractures (39%) than isolated midface fractures (14.5%),1 and maxillary incisors (33.1%) are more commonly affected than mandibular incisors (13.6%), mandibular molars (12.8%), and maxillary premolars (12.6%). 2 Orbitozygomatic complex (also known as zygomaticomaxillary complex [ZMC]) fractures and isolated orbital fractures are less frequently associated with dental injury but should not be missed due to potentially devastating consequences (e.g., orbital compartment syndrome [OCS] leading to vision loss). When general dentists suspect orbital and/or ocular trauma, timely referral should be made to an OMF surgeon for orbital imaging, definitive surgical management, and communication/collaboration with ophthalmological colleagues. General dental practitioners should thus play a key role in the recognition of orbital and ocular trauma, primarily through physical examination and a high index of suspicion, when confronted with dentoalveolar injury.

A basic understanding of orbital and ocular anatomy is important for recognition, diagnosis, and effective communication of injuries to this region. Inside the orbit, there are complex fascial compartments containing the globe, fat, extraocular muscles, blood vessels, nerves, the lacrimal gland, and the lacrimal sac. 3,4 The orbit has a pyramidal shape comprised of four bony walls – inferior, superior, medial, and lateral walls – and an approximate volume of 30-mL. 4 At the apex is the optic foramen, which transmits the optic nerve and ophthalmic artery. The orbital septum and eyelids limit the forward movement of the globe and orbital contents; furthermore, the medial and lateral canthal tendons attach the eyelids to the orbital rim and provide an inflexible anterior boundary to the orbit.

The key components of the focused examination in orbital and ocular trauma include assessment of the following (Table 1): the orbit and external periorbital soft tissues; orbital rims and surrounding bony structures, including palpation for point tenderness and step deformities; pupillary size and reactivity to light; visual acuity and fields (CN II); extraocular muscle function (CNs III, IV, and VI); periorbital skin sensation (V1 and V2 distributions of CN V); and movement of the muscles of facial expression (CN VII). The above-mentioned tests may be performed using instruments available in any dental office, while intraocular pressure measurement and direct ophthalmoscopic examination of the retina, optic nerve, and retinal vessels must be deferred to a specialist.Orbital fractures lie outside the field of view for conventional dental radiographs and orthopantomograms (i.e., panoramic radiographs), but the discriminatory power of a focused physical examination should not be underestimated. Examination of the globe and surrounding tissues should be performed to look for conjunctival hyperemia, conjunctival edema (known as chemosis), and flattening of the anterior chamber (i.e., the space between the cornea and iris). Hyperemia may suggest focal irritation from superficial lacerations or retained foreign bodies; chemosis may indicate occult globe rupture or significant globe contusion; and flattening of the anterior chamber often suggests globe perforation. 6 Widening of the intercanthal distance (known as traumatic telecanthus) usually indicates lateral displacement of a nasal side wall fracture and the corresponding medial canthal tendon attachment (Figs. 4A & 4B). Such fractures of the medial orbit are known as nasoorbitoethmoid (NOE) complex fractures, and are classified based on the lacrimal bone-to-medial canthal tendon relationship.7 The supraorbital, infraorbital, medial, and lateral bony rims should always be palpated for step deformities. Furthermore, CN V–specifically, the V1 and V2 distributions–and CN VII function should be evaluated. The remaining orbital nerves are assessed when testing visual acuity/fields (CN II) and ocular motility (CNs III, IV, and VI).

Fig. 4A, B
A, Equally round, dilated pupils. B, Ipsilateral pupillary constriction and consensual response when penlight is shone into right pupil. C, Relative afferent pupillary defect indicated by lack of ipsilateral pupillary constriction and consensual response when penlight is shone into left pupil.

Pupil evaluation is a measure of ocular function that may be performed on a nonverbal or uncooperative patient. This examination consists of three recordings: (i) the size and shape of each pupil, (ii) reactivity to bright light, and (iii) presence or absence of pupillary constriction during near synkinesis (often referred to as pupillary accommodation). 5 A teardrop-shaped pupil (known as corectopia) often indicates an anterior penetrating injury to the eye, with the point of the teardrop typically oriented toward the laceration.8 As previously mentioned, occult globe perforation should also be suspected when the anterior chamber is flattened, or filled with blood (known as hyphema). Pupil size is not affected by optic nerve function; rather, pupillary constriction is regulated by parasympathetic fibers travelling along the inferior division of CN III, and pupillary dilation is regulated by sympathetic fibers travelling along the ophthalmic nerve (V1 division of CN V). Vision, on the other hand, is dependent upon CN II function.

Reactivity to bright light should be assessed for each pupil using the swinging flashlight test.5 An RAPD occurs when there is a defect along the afferent visual pathway (i.e., at the retina, optic nerve, optic chiasm, and/or optic tract), which impairs the pupillary light reflex. 5,6,9 For example, a penlight shone into the right pupil should elicit equal pupillary constriction in both eyes (Figs. 5A & 5B). By continuing to watch the right pupil while swinging the penlight to the left pupil, the right pupil should be observed to minimally dilate and then constrict once the light has reached the left eye. If both the left and right pupils do not constrict once the penlight has reached the left pupil, this would indicate a left-sided RAPD (Fig. 5C). Finally, assessment of pupillary constriction during near synkinesis is a test of little value in the acute assessment of orbital and ocular trauma; this test is better suited as part of a complex neurological evaluation.

Fig. 5A, B, C
A, Equally round, dilated pupils. B, Ipsilateral pupillary constriction and consensual response when penlight is shone into right pupil. C, Relative afferent pupillary defect indicated by lack of ipsilateral pupillary constriction and consensual response when penlight is shone into left pupil.

Visual acuity and fields should always be assessed as part of an orbital and ocular examination. In the absence of an eye chart, visual acuity may be tested by asking if the patient can read newsprint at two feet. If the patient normally wears corrective lenses, these should be worn for initial and follow-up assessments to maintain consistency. Visual field testing in an awake and fully cooperative patient, however, can be more revealing than measuring visual acuity. 9 There are three parts to the visual field examination: (i) central visual field, (ii) peripheral visual field, and (iii) double simultaneous confrontation. 5 A simple test for central visual field involves asking the patient to obscure one eye and focus on the examiner’s nose at roughly two feet away. While doing so, the patient should be able to see all of the examiner’s facial features, including the ears, without any dark or blurry spots. This test is then repeated for the other eye. Peripheral visual field is assessed by having the examiner and the patient cover a mirror image eye while facing each other at three feet apart. A wiggling finger on the examiner’s outstretched free hand is then slowly brought in from the periphery – while positioned equidistant between his/her head and the patient’s head – until the patient can see it. Assuming normal visual fields in the examiner, the patient’s and the examiner’s peripheral visual field should be roughly coincident. The third part of the visual field analysis, double simultaneous confrontation, is less useful in acute orbital and ocular trauma and may be more appropriately utilized as part of a complex neurological evaluation.

Ocular motility should be assessed to rule out extraocular muscle dysfunction (known as ophthalmoplegia). The first part of the examination determines whether both eyes work in concert while looking straight ahead (known as primary gaze position) at a finger or pencil held at three feet. If the patient can adequately see the object, it is sufficient to ask if one or two images are seen, where duplicate images represent diplopia. The second part of the ocular motility examination tests eye movement in each of the six cardinal positions of gaze: left, right, up-and-in, up-and-out, down-and-out, and down-and-in. This testing can be achieved using the commonly described H-pattern of finger movement. 5 Extraocular movements may be globally restricted due to diffuse periorbital edema, or limited in one meridian (e.g., upgaze and/or downgaze) due to inferior rectus muscle entrapment. For example, children younger than 12-years-old are prone to greenstick orbital floor fractures, which entrap the inferior rectus muscle and restrict upward eye movement.6 These patients often present with nausea and vomiting due to parasympathetic nerve stimulation and require emergency surgical management.

As previously mentioned, direct ophthalmoscopy and intraocular pressure measurement are important tests in the assessment of acute orbital and ocular injuries. Examination of the retina, optic nerve, and retinal vessels may be accomplished using a direct ophthalmoscope, but this technique is difficult to perform through an undilated pupil. An ophthalmologist may use pupil-dilating eye drops (collectively known as mydriatics), which allow for an unrestricted view of the above-mentioned structures. Topical anesthetic eye drops may be used to facilitate intraocular pressure measurement, but this technique may also be better performed by a specialist. In general, normal intraocular pressure ranges from 10- to 22-mm Hg, while a pressure reading of greater than 40-mm Hg indicates OCS, which requires emergency surgical decompression via lateral canthotomy and inferior cantholysis [10]. OCS is a clinical diagnosis for which surgical management should not be delayed; in fact, many cases are managed at the bedside in the emergency department. 10,11

True ophthalmic emergencies, which should never be missed, include OCS, orbital apex syndrome (OAS), and superior orbital fissure syndrome (SOFS). Any sudden increase in orbital pressure can create a compartment syndrome leading to ophthalmic artery compression and ischemia. In the presence of an orbital fracture with maxillary sinus and/or ethmoid sinus communication, air may be forced into the orbit (known as orbital emphysema) during coughing, sneezing, or Valsalva maneuver. 12 Orbital fat may prolapse into the sinus defect, creating a ball-valve mechanism that allows accumulation of air in the tissues and a progressive increase in orbital compartment pressure. Nose blowing can have a similar effect, which is why patients with orbital fractures are advised to follow sinus precautions (i.e., no nose blowing, sneezing with the mouth closed, or forceful coughing) for approximately two to three weeks. As with hematoma-induced OCS, orbital emphysema leading to OCS should also be promptly managed by lateral canthotomy and inferior cantholysis.

OAS and SOFS may both present with ophthalmoplegia and upper lid ptosis due to increased pressure on the structures exiting the superior orbital fissure, but only OAS is associated with vision loss. As previously mentioned, the optic nerve and ophthalmic artery traverse the optic foramen, while CNs III, IV, V (V1 only), and VI pass through the superior orbital fissure. Pressure on the parasympathetic nerve fibers travelling along CN III may result in mydriasis (pupillary dilation) for both OAS and SOFS. These syndromes may be medically managed with intravenous steroids for mild cases, or surgically managed by decompression of the nerve sheath and/or bony canal in more severe cases. Patients with OAS typically have worse functional recovery overall. 12,13

In summary, general dentists are frequently involved in the assessment and management of patients with dentoalveolar injuries and concomitant maxillofacial injuries. While rare, orbital and ocular trauma may not initially be obvious to the patient and may be overlooked by a referring ED physician in the setting of dental injuries. It is thus incumbent upon dental practitioners to conduct a thorough head and neck examination for all facial trauma patients. Implementation of the focused examination outlined in this article may help general dentists to recognize orbital and ocular injuries – especially those requiring urgent management – and make the appropriate referral to an OMF surgeon. With a keen eye for detail, the dentist should thus play an integral role in the recognition and timely referral of orbital and ocular trauma. OH

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References

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  10. McInnes G, Howes DW. Lateral canthotomy and cantholysis: a simple, vision-saving procedure. Can J Emerg Med. 2002;4(1):49-52.
  11. Soparkar CNS, Patrinely JR. The eye examination in facial trauma for the plastic surgeon. Plast Reconstr Surg 2007;120(7):49S-56S.
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About the Authors
 Matthew D. Morrison – Resident (PGY-5), Division of Oral & Maxillofacial Surgery, Department of Dentistry, London Health Sciences Centre, London, Ontario, Canada.
Corresponding author: matthew.morrison@londonhospitals.ca

 

 

Jerrald E. Armstrong – Consultant, Division of Oral & Maxillofacial Surgery, Department of Dentistry, London Health Sciences Centre, London, Ontario, Canada.
Associate Professor, Division of Oral & Maxillofacial Surgery, Schulich School of Medicine & Dentistry, University of Western Ontario, London, Ontario, Canada.
Program Director, Oral & Maxillofacial Surgery Residency, Schulich School of Medicine & Dentistry, University of Western Ontario, London, Ontario, Canada.

Henry J. Lapointe – Consultant, Division of Oral & Maxillofacial Surgery, Department of Dentistry, London Health Sciences Centre, London, Ontario, Canada.
Professor, Division of Oral & Maxillofacial Surgery, Schulich School of Medicine & Dentistry, University of Western Ontario, London, Ontario, Canada.