Browsing by Author "Alphonse, Vanessa D."

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    The Biomechanical Response of the Eye, Face, and Orbit to Primary Blast Overpressure
    Alphonse, Vanessa D. (Virginia Tech, 2015-12-08)
    Combat-related blast injuries are occurring more frequently with the increased use of improvised explosive devices in current military conflicts. Though much research has focused on how the body responds to the relatively low loading rates associated with blunt trauma, little is known regarding the response of the body to the higher loading rates associated with blast trauma. While soldiers are surviving once-lethal blast events due to enhanced protective equipment, injuries such as those to the eye and face that were once considered inconsequential, can now be detrimental to long-term healthcare costs and quality of life. Although it is suggested primary blast overpressure (i.e., the shock wave) can cause severe eye injuries, there remains few empirical data in the literature that confirms this. Adding to this, there are currently no testing standards to assess the effectiveness of personal protective equipment during blast exposure. Expanding upon traditional research techniques within the field of injury biomechanics, the research in this dissertation focuses specifically on developing experimental and physical models of the eye, face, and orbit for blast overpressure exposure. Foremost, a porcine eye model is used to quantify eye injury risk from blast overpressure exposure. Subsequently, these biomechanical data are used to develop a physical model of the eye that can be used in lieu of cadaver specimens for blunt and blast loading. Lastly, military spectacles and goggles are examined for effectiveness at protecting the eye during blast exposure. Combined with detailed computer-aided design geometries, these data can be used to validate computational models of the eye, orbit, and face to blast loading. Results from these tests support one theory that shock waves may enter the skull through the orbit, alluding to future work that is essential to more fully understanding the physiological response of the brain and ocular motor system to blast exposure. Ultimately, the experimental methods and analysis techniques disseminated herein serve as a framework for future experimental work related to blast and other high-rate loading scenarios.
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    Evaluation of Eye Injury Risk from Consumer Fireworks
    Alphonse, Vanessa D.; Kemper, Andrew R. (Brain Injuries and Biomechanics Symposium, 2013-09-19)
    Eye injuries affect approximately two million people annually. Various experimental studies have been performed to evaluate potentially injurious conditions from blunt objects using animal and human cadaver eyes. Experimental data from these studies have been used to develop injury risk curves to predict eye injuries based on projectile parameters such as kinetic energy and normalized energy. Recently, intraocular pressure (IOP) has been correlated to injury risk, which allows eye injuries to be predicted if projectile characteristics are unknown. Additionally, the measurement of IOP and the association of IOP to injury risk in experimental tests has opened up the field to studying eye injury mechanisms from overpressure. The current manuscript presents recent experimental tests that evaluated the response of human cadaver eyes exposed to firework overpressure. Consumer fireworks serve as a model of low level blast, and provides a foundation to studying higher blast overpressures (i.e., that would be observed in military combat). Although some studies state that eye injury can result solely from primary blast (overpressure), there is no empirical evidence in the literature to support this. Future experimental studies should be conducted to assess this statement.
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    Literature Review of Eye Injuries and Eye Injury Risk from Blunt Objects
    Alphonse, Vanessa D.; Kemper, Andrew R. (Brain Injuries and Biomechanics Symposium, 2013-09-19)
    Eye injuries affect approximately two million people annually. Various studies that have evaluated the injury tolerance of animal and human eyes from blunt impacts are summarized herein. These studies date from the late 60s to present and illustrate various methods for testing animal and human cadaver eyes exposed to various blunt projectiles including metal rods, BBs, baseballs, and foam pieces. Experimental data from these studies have been used to develop injury risk curves to predict eye injuries based on projectile parameters such as kinetic energy and normalized energy. Recently, intraocular pressure (IOP) has been correlated to injury risk which allows eye injuries to be predicted when projectile characteristics are unknown. These experimental data have also been used to validate numerous computational and physical models of the eye used to assess injury risk from blunt loading. One such physical model is the the Facial and Ocular CountermeasUre Safety (FOCUS) headform, which is an advanced anthropomorphic device designed specifically to study facial and ocular injury. The FOCUS headform eyes have a biofidelic response to blunt impact and eye load cell data can be used to assess injury risk for eye injuries.