The Pathogenesis of Retinal Damage in Blunt Eye Trauma: Finite Element Modeling

Rossi, Tommaso; Boccassini, Barbara; Esposito, Luca; Iossa, Mario; Ruggiero, Andrew; Tamburrelli, Ciro; Bonora, Nicola

doi:10.1167/iovs.10-6477

Cited by 81 publications

(61 citation statements)

References 33 publications

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“…Constitutive parameters were determined through a reverse engineering calibration procedure that was previously reported, 10 and MSC Dytran 2010 (MSC Software, Santa Ana, CA) was used to run simulations. The orbit volume was assumed to be filled with a viscoelastic solid representing the fat tissue.…”

Section: Constitutive Models and Mechanical Propertiesmentioning

confidence: 99%

Primary Blast Injury to the Eye and Orbit: Finite Element Modeling

Rossi¹,

Boccassini

Esposito

et al. 2012

Invest. Ophthalmol. Vis. Sci.

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PURPOSE. Primary blast injury (PBI) mostly affects air-filled organs, although it is sporadically reported in fluid-filled organs, including the eye. The purpose of the present paper is to explain orbit blast injury mechanisms through finite element modeling (FEM).METHODS. FEM meshes of the eye, orbit, and skull were generated. Pressure, strain, and strain rates were calculated at the cornea, vitreous base, equator, macula, and orbit apex for pressures known to cause tympanic rupture, lung damage, and 50% chance of mortality. RESULTS.Pressures within the orbit ranged between þ0.25 and À1.4 MegaPascal (MPa) for tympanic rupture, þ3 and À1 MPa for lung damage, and þ20 and À6 MPa for 50% mortality. Higher trinitrotoluene (TNT) quantity and closer explosion caused significantly higher pressures, and the impact angle significantly influenced pressure at all locations. Pressure waves reflected and amplified to create steady waves resonating within the orbit. Strain reached 20% along multiple axes, and strain rates exceeded 30,000 s À1 at all locations even for the smallest amount of TNT.CONCLUSIONS. The orbit's pyramidlike shape with bony walls and the mechanical impedance mismatch between fluidlike content and anterior air-tissue interface determine pressure wave reflection and amplification. The resulting steady wave resonates within the orbit and can explain both macular holes and optic nerve damage after ocular PBI. (Invest Ophthalmol Vis Sci. 2012;53:8057-8066) DOI:10.1167/iovs.12-10591 P rimary blast injury (PBI) refers to biological damage caused by the peak incident overpressure (PIO) wave generated by an explosion. Initially described exclusively in hollow, air-filled organs, 1,2 the spectrum of PBI progressively enlarged to encompass fluid-filled organs, including the central nervous system 3,4 and the eye. 3-6Macular holes, choroidal rupture, and optic nerve damage occur relatively frequently after blunt trauma, 7 and although the pathogenic mechanism remains unclear, vitreous traction, 8 globe deformation, differential eye layer stiffness, 9 shockwave propagation, and multiaxial strain 10 likely participate.Finite element modeling (FEM) is a numerical analysis method largely used to simulate multiphysics problems. Previous applications to ophthalmology [11][12][13] and, specifically, to blunt eye trauma 10 have been reported. The purpose of the present paper is to create a computational model of ocular PBI, simulate the propagation of blast waves through the orbit, and explain its pathogenesis. The study was prompted by the observation of macular holes, multiple choroidal ruptures, subretinal bleeding, and optic atrophy after blast exposure, in the absence of any contact with splinters and/or flying objects (Fig. 1). MATERIALS AND METHODS Finite Element ModelingThe eye model has been previously described, 10,14 while orbit and retrobulbar fat tissue were reconstructed based on patient computed tomography scan and magnetic resonance imaging ( Fig. 2; see the Appendix for further technical details on FEM). C...

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Section: Constitutive Models and Mechanical Propertiesmentioning

confidence: 99%

Primary Blast Injury to the Eye and Orbit: Finite Element Modeling

Rossi¹,

Boccassini

Esposito

et al. 2012

Invest. Ophthalmol. Vis. Sci.

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“…The surface of the orbital cavity was reconstructed from magnetic resonance imaging (MRI). Some of the constitutive models and the mechanical properties of the tissues represented in the model were taken from literature [5] and the others were identified in a previous work of the authors [2]. In this latter an inverse engineering approach was adopted to tune the model parameters in order to reproduce Delori's experimental data [6] disregarding the anisotropic and inhomogeneous characteristics of the eye.…”

Section: Methodsmentioning

confidence: 99%

“…Ocular injuries could be a result of a blunt trauma, an impact with an object without penetrating the eyewall. Over 60% of the 2.4 millions of ocular lesions yearly estimated in the United States alone are due to blunt trauma [2].…”

Section: Introductionmentioning

confidence: 99%

The pathogenesis of retinal damage in human eye under impact and blast load

Esposito¹,

Rossi²,

Bonora³

et al. 2012

AIP Conference Proceedings

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Abstract. Human eye subjected to non penetrating impact (blunt-impact) may experience severe damage. The most common type is partial tearing of the retina at specific eye locations. In ophthalmology, based on impact experiment performed by Delori et al. (1967), it is commonly accepted that the mechanism responsible for retinal damage is the vitreous pull-traction action and the equatorial expansion of the sclera. Based on the evidence of a vitrectomized patient who reported retinal damage after blunt impact, an investigation on the possible role of shockwave dynamics in the retinal damage has been performed by means of hydrocode numerical simulation. A FEM model of the eye has been developed and the experiment of Delori et al. has been reproduced. Soft tissues constitutive response has been determined by means of reverse engineering approach. It has been demonstrated that release waves at the retina-choroid interface are generated in the early time of the blunt impact and can cause retina tearing when the eye bulb is still undeformed. This result has been also confirmed for the case of blast-load exposure.

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“…The primary blast shock wave can propagate through the different media of the eye globe and related orbital anatomical structures causing contusion to organs and tissue in the region [3][4]. Such ocular damage resulting from primary blast was initially described by Duke-Elder, and included subconjunctival hemorrhages, traumatic cataract, traumatic uveitis, secondary glaucoma, retinal edema, choroidal rupture, and macular lesions [5].…”

Section: Introductionmentioning

confidence: 99%

“…Finally, computational models using finite element modeling have been characterized to simulate the propagation of blast waves through the orbit and attempt to explain the damage induced by the primary blast per se without the secondary or tertiary injury cofounder [3][4].…”

Section: Introductionmentioning

confidence: 99%

Effects of repetitive low-level blast exposure on visual system and ocular structures

et al. 2015

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Abstract-The purpose of this study was to determine whether repetitive exposure to low-level blasts during military breacher training produces acute and cumulative damage to the ocular tissues or visual system. The effects of low-level blast exposure on high-contrast visual acuity, contrast sensitivity, oculomotor function, color vision, visual field (VF), pupillary light reflex, corneal endothelial cell density (ECD), macular thickness, retinal nerve fiber layer thickness, and cup-to-disc ratio were assessed using a battery of standard clinical ophthalmic tests administered 10 times over a 2-year period. Data from nine male breacher instructors (Cadre) were compared with data from four male breacher engineers (Control). The Cadre group showed higher vertical deviation at near than the Control group over time. The VF mean deviation on the left eye tended to be worse in the Cadre group throughout the study, suggesting a decrease in VF sensitivity (Cadre: -0.20 +/-0.15 dB; Control: 1.05 +/-0.15 dB; p = 0.03). , p = 0.03). These results suggest that even low-level primary blast has the potential to produce occult eye injury.

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The Pathogenesis of Retinal Damage in Blunt Eye Trauma: Finite Element Modeling

Cited by 81 publications

References 33 publications

Primary Blast Injury to the Eye and Orbit: Finite Element Modeling

Primary Blast Injury to the Eye and Orbit: Finite Element Modeling

The pathogenesis of retinal damage in human eye under impact and blast load

Effects of repetitive low-level blast exposure on visual system and ocular structures

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