Computer modelling study of the mechanism of optic nerve injury in blunt trauma

Abstract

Aim: The potential causes of the optic nerve injury as a result of blunt object trauma, were investigated using a computer model. Methods: A finite element model of the eye, the optic nerve, and the orbit with its content was constructed to simulate blunt object trauma. We used a model of the first phalanx of the index finger to represent the blunt body. The trauma was simulated by impacting the blunt body at the surface between the globe and the orbital wall at velocities between 2-5 m/s, and allowing it to penetrate 4-10 mm below the orbital rim. Results: The impact caused rotations of the globe of up to 5000˚/s, lateral velocities of up to 1 m/s, and intraocular pressures (IOP) of over 300 mm Hg. The main stress concentration was observed at the insertion of the nerve into the sclera, at the side opposite to the impact. Conclusions:The results suggest that the most likely mechanisms of injury are rapid rotation and lateral translation of the globe, as well as a dramatic rise in the IOP. The strains calculated in the study should be sufficiently high to cause axonal damage and even the avulsion of the nerve. Finite element computer modelling has therefore provided important insights into a clinical scenario that cannot be replicated in human or animal experiments.A nterior traumatic optic neuropathy and optic nerve avulsion may result from a blunt injury where a foreign object intrudes between the globe and the orbital wall.

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

“…The orbit volume was assumed to be filled with a viscoelastic solid representing the fat tissue. 15 (See the Appendix for details on the constitutive model. )…”

Papillopathie traumatique : à propos d’un cas d’arrachement partiel du nerf optique

“…L'agent intrusif est également responsable d'une déformation du globe qui occasionne une hypertonie oculaire importante et brutale qui rentre éga-lement en jeu dans le mécanisme d'arrachement du nerf optique. Cette hypothèse étiopathogénique suggérée par l'analyse des lésions cliniques a été confirmée par une modé-lisation informatique réalisée par l'équipe de Cirovic et al [25]. En revanche, la translation antérieure du globe ne semble pas rentrer en jeu dans le mécanisme d'avulsion d'après cette étude.…”

Prediction of globe rupture caused by primary blast: a finite element analysis

“…Stitzel et al (2002) predicted globe rupture caused by blunt impact using finite element analysis, which was validated by 22 matched experiments. There have been more recent simulation studies conducted on ocular injuries related to lens injury (Stitzel et al 2005), optic nerve damage (Cirovic et al 2006), globe rupture after PRK and LASIK (Mousavi et al 2012), retinal damage in abusive head trauma (Hans et al 2009;Rangarajan et al 2009) and traumatic retinal detachment (Rossi et al 2011;Liu et al 2013). The current work aimed to develop a blast event model with an implanted eye to predict globe rupture caused by primary blast effects.…”