Orbital Foreign Body
Orbital foreign body (IOrbFB) is recognized by the following codes as per the International Classification of Diseases (ICD) nomenclature:
H05.50 Retained foreign body following wound of unspecified orbit
H05.51 Retained foreign body following wound of right orbit
H05.52 Retained foreign body following wound of left orbit
H05.53 Retained foreign body following wound of bilateral orbit
An orbital foreign body refers to the presence of any foreign object partially or completely within the orbit, with or without penetration or perforation of the globe. Orbital foreign bodies (Orb FB) may be classified in to purely orbital foreign bodies and transorbtial foreign bodies (orbital and adjacent space - intracranial or paranasal sinus involvement). Most commonly accidental, they may be iatrogenic as well (surgical orbital implants). We shall primarily discuss the accidental foreign bodies herewith.
Mechanisms of injury can include, but are not limited to, high velocity projectiles typically encountered during riots, war or war-like situations, accidental injuries during play, industrial accidents, fall from heights, assault with weapons and domestic indoor and outdoor accidents. These include gardening, agricultural accidents, motor vehicle accidents, and informal sports and games.
Risk factors for orbital foreign bodies include a past history of trauma, which could be from sport, violence, battlefield injuries or industrial trauma. Studies have shown that IOrbital FBs tend to occur more commonly in young (mean age range 15-37) and working-aged men (75-96% male). Occasionally they may be incidentally diagnosed following a remote history of trauma with a self sealing wound that was missed, generally conjunctival.
In contrast to intraocular foreign bodies, which penetrate the globe and are localized within, OrbFBs lodge partially or completely within the walls of the orbit and risk injury to its contents: the globe, infraorbital cranial nerves II, III, IV, V, VI, and extraocular muscles. Rarely, a foreign body may enter as an intraocular foreign body and due to a perforating injury of the globe and lodge within the orbit. A retrospective study of metallic orbital foreign bodies showed that 89% of cases were associated with other ocular injuries including corneal abrasion, iritis, retinal detachment, and commotio retinae. Only 7.4% of cases were associated with open-globe injury and surgical exploration of these did not reveal intraocular foreign bodies. Transorbital foreign bodies may involve the paranasal sinuses and intracranial cavity as well.
Primary prevention of both OrbFB and penetrating orbital injuries includes safer work environments, avoidance of high risk behaviors, especially in children and young adults, and assists . Parents should advise children against playing with projectile toys like guns and sticks especially while running. Appropriate shatterproof protective eye/face wear can minimize but not completely eliminate the risk in industrial, sports and battlefield settings, where orbital injuries are seen most often.
The presentation of orbital foreign bodies can vary. When a patient presents with ocular trauma, it is crucial to perform a thorough history and physical examination including looking for wounds of entry. Physicians must urgently rule out open globe injuries and traumatic optic neuropathy. A high index of suspicion is important to minimize the risk of missing a retained OrbFB, particularly if the history is unclear or unwitnessed, such as in pre-verbal children and intoxicated or unconscious adults. A careful history of the nature of the injury may point to the type of foreign body (FB) and depth of penetration. A history of explosion, gunshot wound, or striking of metal upon metal should raise suspicion for orbital or intraocular foreign bodies.A complete ocular and adnexal exam with assessment of the upper cranial nerves is necessary to determine the depth of penetration and neurological status. conjunctival hyperemia, chemosis, and limitation of ocular movements. Symptoms of OrbFB include visual disturbances (decreased vision, double vision), pain, swelling, droopy eyelid, double vision or occasionally may even be asymptomatic (occult foreign bodies).
OrbFB may be occasionally difficult to diagnose mainly when not suspected and occasionally when clinically inconsequential. A detailed history of the time and circumstance of injury should be documented, with particular attention paid to the surrounding environment and potential composition of the foreign material (e.g. bullet, metal fragment, wood, etc). Any orbital trauma especially with perirobital wounds should be approached with a high index of suspicion for an IOrbFB until otherwise proven by exam and detailed imaging. Foreign bodies that are not detected on clinical exam and radiologic procedures may require multiple examinations and additional imaging.
Imaging studies should be used to determine the location of the foreign body and to rule out optic nerve or CNS involvement. In the Emergency Room environment when metallic foreign bodies are suspected or have to be ruled out, plain x-rays in the PA and Lateral views may be performed as a screening examination. However, a non-contrast CT scan of the orbits (axial, coronal, and parasagittal views) and brain is the first line imaging study after trauma. In addition to detecting radiopaque FBs, it may help assess extension into the paranasal sinuses and intracranial space or in late presentation, fluid collections suspicious of orbital abscess. Consultation with the radiologist prior to ordering imaging can be helpful, particularly if there is concern for wood or organic material, The radiologist can then determine if they need to compare the Hounsfield units in any visible "air" in the orbit to determine if there is a wooden FB. MRI may be a helpful adjunct to CT once metallic ferromagnetic foreign bodies have been ruled out especially in cases of chronic orbital inflammation where organic or vegetative material is suspected. MRI is contraindicated if a ferromagnetic metallic foreign body is suspected, and never the initial study of choice after trauma. It should be reserved for high suspicion of wooden or vegetative IOrbFBs or fragments <0.5mm and a negative CT scan. A B-scan Ultrasound(US) may be be performed especially for suspected intraocular foreign or anterior orbital foreign body prior to CT scan, but is generally very technician and technique dependent. Other advantages of ultrasound examination include the ability to detect retinal detachment and hemorrhage, which may alter management. Occasionally a plain radiographs may be adequate in a patient with a reliable history of a single object, a normal eye exam, and a palpable foreign body. However, it should be noted that radiography may underestimate materials such as graphite, plastic, fresh or dry wooden IOrbFB and give less detail than a CT scan without large reduction in radiation exposure.Once an IOrbFB has been confirmed, culture of the injury or the FB should be performed.
Management and extraction of orbital foreign bodies depend greatly on the type of material, size and location and morbidity - visual, motility, infection, etc and finally the expertise of the surgeon.
Types of foreign bodies: Foreign bodies may be either inorganic metallic (eg. steel, lead, iron, copper, etc), nonmetallic (glass, plastic, fiberglass, concrete, rubber); or organic matter (wood, vegetation, animal matter).
Most orbital foreign bodies are metallic in nature and relatively easily visualized on imaging. Small, inert and deeply lodged metallic FBs are usually managed conservatively and well tolerated if left in place. However, this precludes patients from undergoing future MRIs if they are ferromagnetic. Although most metals are inert, some may lead to serious complications (i.e. lead, copper, and iron). Complete surgical removal should be attempted for organic FBs due the increased risk for infection and inflammation, and for inorganic FBs causing orbital complications.
Size of foreign bodies: Most small nonorganic relatively inaccessible IOrbFBs may be left alone without significant subsequent morbidity. Larger FBs pose a high risk to surrounding structures and possible intracranial extension depending on depth, and surgical removal should be attempted with meticulous treatment planning and execution.
If observation is selected over surgical intervention, the patient should be notified and carefully monitored for abscess or fistula formation.
The decision to operate should be individualized, and the physician must weigh the risk of surgery against the risks of retention and delayed complications, including infection. chronic inflammation and fistula formation. Open globe injuries should be immediately repaired before further exploration for OrbFB to prevent loss of ocular contents. Surgical removal is indicated in neurologic compromise, mechanical restriction of eye movements, development of acute or chronic infection, or chronic suppurative reactions to FBs.
Surgical removal should be performed for all organic OrbFBs due to the high risk of infection and inflammation. Inorganic OrbFBs should be removed if they are anterior, accessible and may potentially cause complications such as infection, optic neuropathy, motility disturbance, pain, and/or hemorrhage. Posteriorly located inorganic FBs may often be observed if not causing complications, as primary surgical removal may pose increased risk of structural damage. Finally, timing of removal and repair may be influenced by the time of presentation (from time of initial injury), associated injuries, and degree of inflammation at presentation and expertise of the surgeon.
Patients with OrbFBs should receive tetanus prophylaxis (according to vaccination status) upon presentation. Broad-spectrum antibiotics should be given to cover common pathogens if a recent history of trauma or signs of infection are present, with consideration of anaerobic and even anti fungal coverage, particularly in organic FBs. Furthermore, antibiotics with good blood-brain barrier penetration are recommended due to the proximity of the central nervous system. The most common recommended regimen for a suspected intracranial infection consists of the combination of a third-generation cephalosporin and vancomycin in high doses.
Majority of the morbidity of OrbFBs is from the original injury.
Delayed complications of OrbFBs include:
- Infection and abscess formation
- Sinus infection/mucocele
- Non-infectious inflammation and fibrosis
- Migration or spontaneous extrusion
- Gaze-evoked amaurosis
The most common complication of retained IOrbFBs is infection, which is more common with organic FBs and depends on the initial organism load. The use of broad-spectrum antibiotics may contribute to a delayed development of infection.
Outcomes depend on severity of inciting trauma, material and location of the foreign body. Anteriorly located FBs without penetration of the globe and good visual acuity on presentation were associated with a better prognosis and visual acuity. Studies have shown that in cases with no globe involvement, no subsequent loss of vision was observed. Organic materials have increased risk of causing endophthalmitis and CNS infections. Surgical removal confers its own set of complications including endophthalmitis, retinal detachment, and proliferative vitreoretinopathy. However, studies have found no decrease in vision following surgical intervention. Postoperative visual loss has been reported at rates of 2.5 to 4%.
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