Evaluation of Different Projectiles in Matched Experimental Eye Impact Simulations

Abstract

Eye trauma resuits in 30,000 cases of hiindness each year in tiie United States and is tiie second leading cause of monocular visual impairment. Eye injury is caused by a wide variety of projectile impacts and loading scenarios with common sources of trauma being motor vehicle crashes, military operations, and sporting impacts. For the current study, 79 experimental eye impact tests in literature were computationally modeled to analyze global and localized responses of the eye to a variety of blunt projectile impacts. Simulations were run with eight different projectiles (airsoft pellets, baseball, air gun pellets commonly known as BBs, blunt impactor, paintball, aluminum, foam, and plastic rods) to characterize effects of the projectile size, mass, geometry, material properties, and velocity on eye response. This study presents a matched compari.son of experimental test results and computational model outputs including stress, energy, and pressure used to evaluate risk of eye injury. In general, the computational results agreed with the e.xperimental results. A receiver operating characteristic curve analysis was used to establish the stress and pressure thresholds that best discriminated for globe rupture in the matched experimental tests. Globe rupture is predicted by the computational simulations when the corneoscleral stress exceeds 17.21 MPa or the vitreous pressure exceeds 1.01 MPa. Peak stresses were located at the apex of the cornea, the iimbus, or the equator depending on the type of projectile impacting the eye. A multivariate correlation analysis revealed that area-normalized kinetic energy was the best single predictor of peak stress and pressure. Additional incorporation of a relative size parameter that relates the projectile area to the area of the eye reduced stress response variabititv and max be of importance in eye injury prediction. The modeiing efforts shed light on the injury response of the eye when subjected to a variety of biunt projectile impacts atul further validate the eye model's ability to predict globe rupture. Results of this study are relevant to the design and reguiation of safety systems and equipment to protect against eye injury.

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

“…Numerical simulation has been considered as an effect method to investigate ocular trauma (Uchio et al 1999(Uchio et al , 2003Stitzel et al 2002Stitzel et al , 2005Gray et al 2011;Weaver et al 2011). This method not only allows unmixed explosion condition on the eye but also provides a quantitative analysis of the injuries.…”

Lateral Impact Validation of a Geometrically Accurate Full Body Finite Element Model for Blunt Injury Prediction

“…55 Finite element analysis (FEA) has commonly been used as a computer modeling tool in studying blunt injury biomechanics, such as with traumatic injury to the eye. 53,54 With material models for soft tissues such as the spleen 25 becoming better developed, human body finite element models (FEMs) can more accurately predict injuries. Validated human body FEMs have the potential to determine local injury criteria (i.e., stresses and strains) that are difficult to determine experimentally, thereby providing an advantage in safety system and injury mitigation research.…”

Finite element modelling of cornea mechanics: a review

“…Weaver et al (56) implemented a numerical model of eye impact that considered a variety of blunt projectiles and loading conditions and was based on many experimental impact tests. They investigated the effects of different projectile mass, size, material properties, and velocity on the response of the eye to impact.…”