Blast-related ocular trauma

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Blast-related ocular trauma comprises a specialized subgroup blast injuries which cause penetrating and blunt force injuries to the eye and its structure. The incidence of ocular trauma due to blast forces has increased dramatically with the introduction of new explosives technology into modern warfare. The availability of these volatile materials, coupled with the tactics of contemporary terrorism, has caused a rise in the number of homemade bombs capable of extreme physical harm.

Contents

Military classification of improvised explosive devices

The United States Department of Defense classifies IEDs as explosive machines that are constructed exclusively (i.e., without mass production) and result in the direct physical harm of surrounding individuals. The use of these bombs by insurgents has been the number one cause of death and injury among Coalition soldiers since the start of Operation Iraqi Freedom in April 2003. [1] Detonation of the IED occurs remotely or as victim-induced mechanical disturbance. [2] [3] Further classification of IEDs falls under the mechanism of delivery – vehicle-based, boat-borne, animal-borne, suicide bomber – and the resultant effect upon detonation:

Explosion physics

The discharge of a bomb is characterized by the near-instantaneous sublimation of solids or rapid vaporization of liquids into the gas phase. The amount of explosive materials used, the concentration and identity of secondary materials incorporated into bomb design, and the location and height of bomb placement all determine the magnitude of the explosion. The gas formed displaces the surrounding medium – usually air – and causes a dramatic increase in pressure that forms a characteristic blast wave, often referred to as the leading shock wave. Physically, this wave is characterized as a non-linear, discontinuous wave front that features infinite amplitude and accompanying acoustic pressure wave that may generate a pressure as high as 100MPa in a time as short as one microsecond. This peak pressure, or blast overpressure point, generates a positive pressure during blast wave propagation and results in the dispersal of positive pressure across the blast radius. This positive pressure phase is immediately followed by a period of negative pressure relative to pre-blast conditions; this phase may also account for injuries sustained during a blast. [5] [6]

Impact of explosion upon individuals in the blast radius

The prevalence of mines in Operation Iraqi Freedom and Operation Enduring Freedom has made them the most frequent mechanism of injury behind the traumatic “signature” in modern warfare, blast-induced traumatic brain injury (bTBI). Whereas body armor has lowered the incidence of death due to collapse of gas-filled organs (the most frequent cause of blast-related deaths prior to Operation Desert Storm) healthcare providers must now develop methods for treating bTBI. Despite their frequency on the warfront, the home-produced nature of these mines makes classifying patient presentations difficult for military healthcare providers. The majority of lethal bTBIs reveal axonal shearing as the mechanism of fatality, with the greatest amount of nerve fiber and vascular shearing occurring in the frontal and temporal lobes.

Biophysicists have implicated acoustic impedance, or the ratio of acoustic pressure to particle velocity, as a factor contributing to blast damage in vivo. Wave transitions between tissues with significantly different acoustic impedances, particularly between the external environment and bone, causes focal mechanical damage as a result of wave energy dissipation. Current research has implicated the importance of a histological component in blast trauma; patients exposed to blast waves often present with elongation and/or splitting of cells due to the shear stress of a shockwave. This cellular damage often follows the direction of wave propagation. [1] [5] Patient distance from the epicenter, materials employed in the bomb design, and confinement of the bomb all determine the degree of trauma incurred by patients exposed to bombings. Additionally, skull size and geometry, the degree of tissue penetration by the wave, and a possible “lens effect” due to wave reflection upon incidence with the concave calvarium and/or dissipation in the gas-filled sinuses may further complicate wave transmission. [1] [2] [3] Additionally, researchers have implicated both the auditory canals and the orbitals as potential routes for wave propagation into the central nervous system [5] [7] [8]

Ocular trauma is the fourth most common injury sustained in military combat today. In a pool of 387 randomly selected soldiers injured by blast trauma in Operation Iraqi Freedom, 329 (89%) sustained ocular trauma. [1] [2] [3] Emergency treatment of resulting injuries falls under the realm of emergency care and effective patient triage, often incorporating protocols for blunt and penetrating trauma. As a result, physicians have devised a concise algorithm for the treatment of patients with ocular injuries secondary to blast trauma. [1]

Mechanism of injury

Ocular trauma may result from primary blast exposure. Spallation forces arise as the blast wave displaces a dense medium across a less dense interface, and inertial forces may cause displacement of optical structures. Primary blast ocular trauma therefore comprises non-penetrating mechanical injuries such as hyphemas, ruptured globes, conjunctival hemorrhage, serous retinitis, and orbital fracture. [4] [9] However, ocular trauma most commonly falls under the realm of secondary blast injuries, in which debris displaced by the blast overpressure and resultant blast wave causes physical trauma to the eye and/or orbital. Therefore, secondary blast ocular trauma is distinguished by penetrating- or blunt-force injury to any of structural component of the eye or orbital; open globe injuries, adnexal lacerations of the lacrimal system, eyelids, and eyebrows comprise the majority of injuries in this group. [2] [3]

Skull flexure

Within the last two decades, researchers have reconsidered the role of the skull in bTBI. While it was originally considered that the skull remained static upon contact with the primary wave front, clinically significant skull flexure has been documented in vivo with rats exposed to blast waves and with model human heads exposed to blast conditions. In contact with a blast wave, the skull becomes elastic due to its deformable foundation – the external environment, the cerebrospinal fluid of the dura, and the brain itself. During a blast, the brain collides with the dynamic skull and rebounds in accordance with localized cranial pressure spikes. This trauma may account for the localized axonal injuries that characterize bTBI. Chavko et al. (2010) explored cranial position as a function of bTBI severity, finding that rats directly facing the blast wave front featured the highest intracranial amplitude and pressure duration periods (in comparison with rats perpendicular to the wave front and those facing away from the blast wave) [8] Alessandra Dal Cengio Leonardi's group at Wayne State University expanded upon the skull flexure hypothesis in rat models, further correlating increased age and body mass to increases in intracranial pressure for rats in front-facing bTBI. Chavko's group remarked further on the role of Kevlar armor in fluid pressure damage to neurovasculature, finding that subcortical hemorrhage seen in bTBI patients has been linked to local pressurization rather than vascular hydrodynamics. [8] [10]

Assessment and treatment in the military setting

The majority of blast-related ocular injuries occur in soldiers who present with other life-threatening injuries that require immediate intervention. Current Combat Support Hospital (CSH) protocol requires the surgical stabilization of any life-threatening injuries, as well as hemodynamic stability, prior to initial eye evaluation and surgical repair. Therefore, initiation of emergency ophthalmic care often occurs hours after injury. Initial examination by a military ophthalmologist begins with gross examination of each eye and orbital. 73-82% of all ocular injuries resulting from mine explosions are due to fragmentation of shrapnel upon detonation, so gross anatomical inspection by penlight may not rule out open globe injury. [2] Harlan JB, Pieramici DJ. Evaluation of patients with ocular trauma. Ophthalmol Clin North Am. 2002; 15(2):153-61./ref> Computerized tomography (CT) may detect foreign matter and aid the clinician in determining the presence of an open-globe injury.

Closed globe injuries

Current military standard employs the Birmingham Eye Trauma Terminology System (BETTS) and Ocular Trauma Classification Group to define and treat blast injuries. Trauma is further split into two distinct groups: closed globe injury and open globe trauma. [3] Treatment of closed globe trauma begins with the division of the eye into zones, each with unique anatomical structures and injury patterns:

Open Globe Injuries

The presence of an open globe injuries may be determined by clinical examination and CT. However, full globe exploration with 360-degree removal of the conjunctiva (periotomy), separation of the rectus muscles, and subsequent examination of the sclera remains the most effective way to determine whether or not the globe has been injured. During exploratory surgery, foreign debris may be removed with microsurgical tools by inspection under the operating room microscope. Globe lacerations are typically repaired as far posteriorly as possible to prevent any further deficits in visual acuity. Lacerations posterior to the exposed area are not sutured; attempts to seal these injuries often results in the extrusion of intraocular components. Healing of these injuries occurs naturally by scarring of dorsal orbital fat to the sclera. [2] [3] If a clinically significant increase in intraocular pressure is detected with orbital compartment syndrome, the ophthalmologist may perform an emergency canthotomy on the lateral canthus. Canalicular injuries, as well as lid lacerations, are also commonly repaired in the military hospital setting. [2] [3] Suturing the laceration after the removal of foreign bodies depends on the location of global fissure: 10-0 nylon with cyanoacrylate glue is commonly used on the cornea, and processed human pericardium may be employed if it is surgically available. Globe closure of the limbus and sclera requires 9-0 and 8-0 nylon, respectively. [2]

If damage to the globe is irreparable, the ophthalmologist may conduct a primary enucleation, evisceration, or exenteration in the combat hospital. 14% of globe injuries sustained during Operation Iraqi Freedom have required enucleation. Implantation of an oculoplastic silicone sphere or similar device commonly follows these procedures. [2] [3]

Post-Operative Care

Post-operative care for patients with blast-related ocular trauma occurs in tertiary care facilities. Patients with closed globe injuries require observation and follow-up examination with an optometrist, including slit lamp microscope and dilated fundus inspection. Those who have been treated for open-globe repairs often experience a delay of post-operative treatment that ranges from 10 to 14 days after injury. This period is due to the treatment of other life-threatening injuries, as well as the necessity for accurate estimation of visual acuity outside of inflammation due to injury and surgical intervention. [1] [2] [9]

In patients with facial burns, exposure keratopathy, or chronic epiphora, an ophthalmologist may suggest eyelid reconstruction surgery. Depending on the severity of physical trauma sustained, surgical realignment of the extraocular muscles may relieve strabismus. Realignment of the extraocular muscles is also indicated in chronic diplopia that occurs within 20-degrees of the visual field. All patients that have sustained a traumatic brain injury in the absence of ocular trauma are still recommended to obtain examination by an optometrist. Outside of the treatment facility, these patients must monitor any signs of late-onset ocular pathologies secondary to the bTBI, including decreased visual/reading ability and speed, photophobia, blurred vision, reduced accommodation abilities, and headaches. [2] [9]

Visual Outcomes

Visual outcomes for patients with ocular trauma due to blast injuries vary, and prognoses depend upon the type of injury sustained. The majority of poor visual outcomes arise from perforating injuries: only 21% of patients with perforating injuries with pre-operative light perception had a final best-corrected visual acuity (BCVA) better than 20/200. Collectively, patients who experienced choroidal hemorrhage, perforated or penetrated globes, retinal detachment, traumatic optic neuropathy, and subretinal macular hemorrhage carried the highest incidence rates of BCVAs worse than 20/200. Reports from Operation Iraqi Freedom (OIF) indicate that 42% of soldiers with globe injuries of any kind had a BCVA greater than or equal to 20/40 six months after injury, and soldiers with intraocular foreign bodies (IOFBs) retained 20/40 or better vision in 52% of studied cases. [1] [2] [3]

Globe perforation, oculoplastic intervention, and neuro-ophthalmic injuries contribute significantly to reported poor visual outcomes. 21% of tertiary centers treating patients exposed to blast trauma reported traumatic optic neuropathy (TON) in their patients, although avulsion of the optic nerve and TON were reported in only 3% of combat injuries. [2] In the event that a victim of globe penetrating trauma cannot perceive any light within two weeks of surgical intervention, the ophthalmologist may choose to enucleate as a preventative measure against sympathetic ophthalmia. However, this procedure is extremely rare, and current reports indicate that only one soldier in OIF has undergone enucleation in a tertiary care facility to prevent sympathetic ophthalmia. [2] [3]

Prevention

Eye armor

Prevention of ocular trauma is most effective when soldiers wear polycarbonate eye armor correctly in the battlefield. For Operation Iraqi Freedom and Operation Enduring Freedom, the United States Military have made Ballistic Laser Protective Spectacles (BLPS), Special Protective Eyewear Cylindrical System (SPECS), and Sun/Wind/Dust Goggles (SWDG) available to combatants and associated personnel. These forms of eye protection are available in non-prescription and prescription lenses, and their use has been made mandatory at all times when soldiers are in areas of potential conflict. Despite their proven record of protection against secondary blast trauma, soldier compliance remains low: 85% of soldiers afflicted ocular trauma in the first year of OEF were not wearing their protective lenses at the time of detonation. While 41% of soldiers could not recall whether or not they were wearing eye protection at the time of detonation, 17% of casualties were wearing eye protection while 26% of casualties were not. Among this group, the poorest visual prognoses were documented in individuals who did not wear eye protection. [2] [11] The lack of compliance has been attributed to complaints about comfort, stylishness, and “misting” of the lenses when in the field. BLPS and SPECS offer the same line of protection against secondary trauma as the SWD goggles, and these lenses may overcome the complaints many soldiers have with their military-issue goggles. [8]

Eye Armor and the Primary Blast Wave Trauma

Despite the success of goggles and lenses against ballistic and secondary trauma, BLPS, SPECS, and SWDG forms of eye armor do not protect against primary-blast injuries. The space between the lenses and the eyes promotes sonic wave diffraction, and current efforts to eradicate ocular trauma due to the primary blast wave have been unsuccessful due to this lens-eye air interface. [2]

Additionally, current researchers have correlated helmet design to an amplification of waves that may cause bTBI. Moss et al. (2009) used model human heads outfitted with helmets approved for use in OEF and OIF and subjected them to blast waves at 194G for 2.1 milliseconds. These helmets, the Modular Integrated Communications Helmet (MICH) feature a mesh netting that offers comfort between the wearer's head and the helmet's Kevlar shell. While effective against ballistic trauma, Moss's group reported that skull flexure is amplified by the air interface between the helmet and the skull. This space may amplify the effects of bTBI, and the group suggested that a foam connection between the helmet and the wearer's head may diminish the effects of the peak pressure wave during an explosion. [11]

BrainPort Vision Device

A tremendous amount of the research surrounding war-related ocular trauma has come from the Academic Department of Military Surgery and Trauma (ADMST) In conjunction with Wicab Industries, the ADMST has developed the BrainPort Vision Device, a sensory substitute for soldiers blinded in service. The device uses the tongue, coupled with a camera mounted on a pair of sunglasses, to provide the user with an electrotactile depiction of the environment. After calibration and practice, the user may interpret objects, shapes, and patterns in their immediate surroundings.

Related Research Articles

<span class="mw-page-title-main">Head injury</span> Serious trauma to the cranium

A head injury is any injury that results in trauma to the skull or brain. The terms traumatic brain injury and head injury are often used interchangeably in the medical literature. Because head injuries cover such a broad scope of injuries, there are many causes—including accidents, falls, physical assault, or traffic accidents—that can cause head injuries.

<span class="mw-page-title-main">Optic nerve</span> Second cranial nerve, which connects the eyes to the brain

In neuroanatomy, the optic nerve, also known as the second cranial nerve, cranial nerve II, or simply CN II, is a paired cranial nerve that transmits visual information from the retina to the brain. In humans, the optic nerve is derived from optic stalks during the seventh week of development and is composed of retinal ganglion cell axons and glial cells; it extends from the optic disc to the optic chiasma and continues as the optic tract to the lateral geniculate nucleus, pretectal nuclei, and superior colliculus.

Photophobia is a medical symptom of abnormal intolerance to visual perception of light. As a medical symptom, photophobia is not a morbid fear or phobia, but an experience of discomfort or pain to the eyes due to light exposure or by presence of actual physical sensitivity of the eyes, though the term is sometimes additionally applied to abnormal or irrational fear of light, such as heliophobia. The term photophobia comes from Greek φῶς (phōs) 'light' and φόβος (phóbos) 'fear'.

<span class="mw-page-title-main">Eye surgery</span> Surgery performed on the eye or its adnexa

Eye surgery, also known as ophthalmic surgery or ocular surgery, is surgery performed on the eye or its adnexa. Eye surgery is part of ophthalmology and is performed by an ophthalmologist or eye surgeon. The eye is a fragile organ, and requires due care before, during, and after a surgical procedure to minimize or prevent further damage. An eye surgeon is responsible for selecting the appropriate surgical procedure for the patient, and for taking the necessary safety precautions. Mentions of eye surgery can be found in several ancient texts dating back as early as 1800 BC, with cataract treatment starting in the fifth century BC. It continues to be a widely practiced class of surgery, with various techniques having been developed for treating eye problems.

<span class="mw-page-title-main">Blast injury</span> Type of physical trauma

A blast injury is a complex type of physical trauma resulting from direct or indirect exposure to an explosion. Blast injuries occur with the detonation of high-order explosives as well as the deflagration of low order explosives. These injuries are compounded when the explosion occurs in a confined space.

<span class="mw-page-title-main">Traumatic brain injury</span> Injury of the brain from an external source

A traumatic brain injury (TBI), also known as an intracranial injury, is an injury to the brain caused by an external force. TBI can be classified based on severity ranging from mild traumatic brain injury (mTBI/concussion) to severe traumatic brain injury. TBI can also be characterized based on mechanism or other features. Head injury is a broader category that may involve damage to other structures such as the scalp and skull. TBI can result in physical, cognitive, social, emotional and behavioral symptoms, and outcomes can range from complete recovery to permanent disability or death.

Closed-head injury is a type of traumatic brain injury in which the skull and dura mater remain intact. Closed-head injuries are the leading cause of death in children under 4 years old and the most common cause of physical disability and cognitive impairment in young people. Overall, closed-head injuries and other forms of mild traumatic brain injury account for about 75% of the estimated 1.7 million brain injuries that occur annually in the United States. Brain injuries such as closed-head injuries may result in lifelong physical, cognitive, or psychological impairment and, thus, are of utmost concern with regards to public health.

<span class="mw-page-title-main">Eye examination</span> Series of tests assessing vision and pertaining to the eyes

An eye examination, commonly known as an eye test, is a series of tests performed to assess vision and ability to focus on and discern objects. It also includes other tests and examinations pertaining to the eyes. Eye examinations are primarily performed by an optometrist, ophthalmologist, or an orthoptist. Health care professionals often recommend that all people should have periodic and thorough eye examinations as part of routine primary care, especially since many eye diseases are asymptomatic.

<span class="mw-page-title-main">Eye injury</span> Physical or chemical injuries of the eye

Physical or chemical injuries of the eye can be a serious threat to vision if not treated appropriately and in a timely fashion. The most obvious presentation of ocular (eye) injuries is redness and pain of the affected eyes. This is not, however, universally true, as tiny metallic projectiles may cause neither symptom. Tiny metallic projectiles should be suspected when a patient reports metal on metal contact, such as with hammering a metal surface. Corneal foreign bodies are one of the most common preventable occupational hazards. Intraocular foreign bodies do not cause pain because of the lack of nerve endings in the vitreous humour and retina that can transmit pain sensations. As such, general or emergency department doctors should refer cases involving the posterior segment of the eye or intraocular foreign bodies to an ophthalmologist. Ideally, ointment would not be used when referring to an ophthalmologist, since it diminishes the ability to carry out a thorough eye examination.

<span class="mw-page-title-main">Lateral rectus muscle</span> Muscle on lateral side of the eye

The lateral rectus muscle is a muscle on the lateral side of the eye in the orbit. It is one of six extraocular muscles that control the movements of the eye. The lateral rectus muscle is responsible for lateral movement of the eyeball, specifically abduction. Abduction describes the movement of the eye away from the midline, allowing the eyeball to move horizontally in the lateral direction, bringing the pupil away from the midline of the body.

<span class="mw-page-title-main">Hyphema</span> Hemorrhage in the front chamber of the eye

Hyphema is the medical condition of bleeding in the anterior chamber of the eye between the iris and the cornea. People usually first notice a loss or decrease in vision. The eye may also appear to have a reddish tinge, or it may appear as a small pool of blood at the bottom of the iris in the cornea. A traumatic hyphema is caused by a blow to the eye. A hyphema can also occur spontaneously.

<span class="mw-page-title-main">Cerebral contusion</span> Bruise of the brain tissue

Cerebral contusion, a form of traumatic brain injury, is a bruise of the brain tissue. Like bruises in other tissues, cerebral contusion can be associated with multiple microhemorrhages, small blood vessel leaks into brain tissue. Contusion occurs in 20–30% of severe head injuries. A cerebral laceration is a similar injury except that, according to their respective definitions, the pia-arachnoid membranes are torn over the site of injury in laceration and are not torn in contusion. The injury can cause a decline in mental function in the long term and in the emergency setting may result in brain herniation, a life-threatening condition in which parts of the brain are squeezed past parts of the skull. Thus treatment aims to prevent dangerous rises in intracranial pressure, the pressure within the skull.

<span class="mw-page-title-main">Blunt trauma</span> Trauma to the body without penetration of the skin

Blunt trauma, also known as blunt force trauma or non-penetrating trauma, describes a physical trauma due to a forceful impact without penetration of the body's surface. Blunt trauma stands in contrast with penetrating trauma, which occurs when an object pierces the skin, enters body tissue, and creates an open wound. Blunt trauma occurs due to direct physical trauma or impactful force to a body part. Such incidents often occur with road traffic collisions, assaults, and sports-related injuries, and are notably common among the elderly who experience falls.

Optic neuropathy is damage to the optic nerve from any cause. The optic nerve is a bundle of millions of fibers in the retina that sends visual signals to the brain.

The Brain Trauma Foundation (BTF) was founded in 1986 to develop research on traumatic brain injury (TBI). Since its formation the foundation's mission has expanded to improving the outcome of TBI patients nationwide through working to implement evidence-based guidelines for prehospital and in-hospital care, quality-improvement programs, and coordinating educational programs for medical professionals.

Primary and secondary brain injury are ways to classify the injury processes that occur in brain injury. In traumatic brain injury (TBI), primary brain injury occurs during the initial insult, and results from displacement of the physical structures of the brain. Secondary brain injury occurs gradually and may involve an array of cellular processes. Secondary injury, which is not caused by mechanical damage, can result from the primary injury or be independent of it. The fact that people sometimes deteriorate after brain injury was originally taken to mean that secondary injury was occurring. It is not well understood how much of a contribution primary and secondary injuries respectively have to the clinical manifestations of TBI.

<span class="mw-page-title-main">Focal and diffuse brain injury</span> Medical condition

Focal and diffuse brain injury are ways to classify brain injury: focal injury occurs in a specific location, while diffuse injury occurs over a more widespread area. It is common for both focal and diffuse damage to occur as a result of the same event; many traumatic brain injuries have aspects of both focal and diffuse injury. Focal injuries are commonly associated with an injury in which the head strikes or is struck by an object; diffuse injuries are more often found in acceleration/deceleration injuries, in which the head does not necessarily contact anything, but brain tissue is damaged because tissue types with varying densities accelerate at different rates. In addition to physical trauma, other types of brain injury, such as stroke, can also produce focal and diffuse injuries. There may be primary and secondary brain injury processes.

<span class="mw-page-title-main">Facial trauma</span> Medical condition

Facial trauma, also called maxillofacial trauma, is any physical trauma to the face. Facial trauma can involve soft tissue injuries such as burns, lacerations and bruises, or fractures of the facial bones such as nasal fractures and fractures of the jaw, as well as trauma such as eye injuries. Symptoms are specific to the type of injury; for example, fractures may involve pain, swelling, loss of function, or changes in the shape of facial structures.

Traumatic brain injury modeling replicates aspects of traumatic brain injury (TBI) as a method to better understand what physically happens to the brain. Researchers use a variety of models for this process, with different models able to replicate certain aspects of TBI while also producing their own limitations.

Open-globe injuries are full-thickness eye-wall wounds requiring urgent diagnosis and treatment.

References

  1. 1 2 3 4 5 6 7 Ramasamy A, Harrisson SE, Clasper JC, Stewart MP., Injuries from roadside improvised explosive devices. J Trauma 2008; 65(4):910-4.
  2. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 Weichel ED, Coyler MH. Combat ocular trauma and systemic injury. Curr Opin Ophthalmol 2008; 19(6):519-25.
  3. 1 2 3 4 5 6 7 8 9 10 Wolf SJ, Bebarta MV, Bonnet CJ. Blast injuries. Lancet 2009; 374(9687):405-15.
  4. 1 2 United States Department of Defense., Joint Publication 1-02, Department of Defense Dictionary of Military and Associated Terms. 2008, amended 2011. 171.
  5. 1 2 3 Leonardi ADC, Bir CA, Ritzel DV, VandeVord PJ. Intracranial pressure increases during exposure to a shock wave. J Neurotrauma. 2011. 2011. 28(1):85-94.
  6. ↑ Nakagawa A, Manley GT, Gean AD. Mechanisms of primary blast-induced traumatic brain injury: Insights from shock wave research. J Neurotrauma. 2010. Accepted for publication; available online at http://www.liebertonline.com/doi/pdfplus/10.1089/neu.2010.1442
  7. ↑ Nakagawa A, Manley GT, Gean AD. Mechanisms of primary blast-induced traumatic brain injury: Insights from shock wave research. J Neurotrauma. 2010. Accepted for publication; available online at http://www.liebertonline.com/doi/pdfplus/10.1089/neu.2010.1442.
  8. 1 2 3 4 Chavko M, Watanabe T, Adeeb S, Lankasky J, Ahlers ST, McCarron RM. Relationship between orientation to a blast and pressure wave propagation inside the rat brain. Journal of Neuroscience Methods. 2010. 30(1):61-66.
  9. 1 2 3 Harlan JB, Pieramici DJ. Evaluation of patients with ocular trauma. Ophthalmol Clin North Am. 2002; 15(2):153-61.
  10. ↑ Long JB, Bentley TL, Wessner KA, Cerone C, Sweeny S, Bauman RA. Blast overpressure in rats: Recreating a battlefield injury in the laboratory. J Neurotrauma. 2009. 26:827-40.
  11. 1 2 Thomas R, McManus JG, Johnson A, Mayer P, Wade C, Holcomb JB. Ocular injury reduction from ocular protection use in current combat operations. J Trauma. 2009. 66(4):S99-S103.
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