THE DEVELOPMENT AND VALIDATION OF A BIOFIDELIC SYNTHETIC EYE FOR THE FACIAL AND OCULAR COUNTERMEASURE SAFETY (FOCUS) HEADFORM ERIC ALLEN KENNEDY Dissertation submitted to the Faculty of the Virginia Polytechnic Institute and State University in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Biomedical Engineering Stefan M. Duma, Ph.D., Chair H. Clay Gabler, Ph.D. Joel D. Stitzel, Ph.D. Michael L. Madigan, Ph.D. Ian P. Herring, D.V.M., M.S. P. Gunnar Brolinson, D.O. August 3, 2007 Blacksburg, Virginia Keywords: FOCUS Headform, Eye, Injury, ATD Headform, Risk Function Copyright 2007, Eric A. Kennedy THE DEVELOPMENT AND VALIDATION OF A BIOFIDELIC SYNTHETIC EYE FOR THE FACIAL AND OCULAR COUNTERMEASURE SAFETY (FOCUS) HEADFORM Eric Allen Kennedy ABSTRACT There are over 1.9 million eye injuries per year in the United States with over 30,000 patients left blind in at least one eye as a result of trauma. Some of the most severe eye injuries can occur in automobile accidents and from sports related impacts. Eye injuries in the military environment are even more prevalent and are generally more severe than eye injuries to civilians. The rate of eye injuries has dramatically increased in warfare in recent years, rising from 2% of all casualties during World War I and World War II to over 13% of all combat injuries in Operation Desert Storm. While many of the conflict-related eye injuries are caused by shrapnel and other debris, nearly 25% of the injuries are also caused by blunt trauma from motor vehicle and helicopter crashes, falling, and direct hits from blunt objects. In order to develop safety countermeasures effective at preventing these eye injuries, as well as evaluate the eye injury potential of different impacts, it is desirable to have the capability for distinguishing between injurious and non-injurious eye impacts. Current anthropometric test device (ATD) headforms lack instrumentation and facial features to allow detailed assessment of eye or discrete facial injuries. Therefore, the purpose of this dissertation is to present the development and validation of the Facial and Ocular CountermeasUre Safety (FOCUS) headform’s synthetic eye and orbit and corresponding eye injury risk criteria. ACKNOWLEDGEMENTS Before I can feel the relief and celebration of finishing this dissertation I will have to figure out a way to adequately thank the many people who all were an integral part of making this all possible. First, you cannot reach academic success without having a good teacher. For the past 5 years, working under Stefan Duma, I have had an enormity of opportunities to watch, learn, and participate – more than I ever could have hoped or ever dreamed of. On the occasions where I have achieved success, it is in no small part to the role he played in mentoring me along the way. I will never be able to say thanks enough, but I do hope to offer similarly effective advice to my own students in the future. To the remainder of my committee: Joel Stitzel and Clay Gabler, whom I have interacted with almost every day, I can only say thanks for so often being an example for so much of which I hope to follow. Mike Madigan, thank you for the advice and conversations and for never failing to have a great answer to even the dumbest of questions. Gunnar Brolinson and Ian Herring, thanks to both of you for the medical perspective that you brought to our conversations and for always finding the time. To my all of my friends from Maryland, Virginia Tech, elsewhere, but especially the Center for Injury Biomechanics. Sarah Manoogian, my office mate for most of my time at Virginia Tech and a wonderful friend that I will miss seeing every day. Doug Gabauer and Craig McNally for motivating from opposite perspectives on ways to improve a 5k time (and many other memories as well). Andrew Kemper for many “fun” (if that is the right word) testing “experiences” (I know that is the right word). And of course, literally everyone else who played an equally important role in providing me (and Schatzie – thank you Kate and Jared) a strong VT family. I must thank of course my family – who I know are proud to know that I have finished and who offered so much support along the way: Mom and Dad, Grandmom and Granddad, Pop-Pop and Grandmal (who I know are just as proud looking down on me), Minda and Dan, Nancy and Tina, Mom and Dad McLaughlin, and my new brother and sister-in-law and favorite niece (Megan)!!! … which of course implies that a huge thank you is owed to a wonderful woman, who I know that I would not have made it down this road without… To Carol, who toughed out four-hour drives to make this all work out (after she toughed out ten- hour drives to make this all work out). You have never failed to support me for anything that I have wanted, or needed to do, to get to this point. More amazingly, you have never expected nearly as much from me in return, and I hope that this accomplishment and our road in the future is some form of repayment for that. Thank you for always being there for me… and the dog. And finally, to Schatzie the Shiloh Shepherd, who guarded the house by day and greeted me with a wagging tail (and tongue) as I got home at night. Day to day, no matter what any of these people think, it was probably you the most who helped me keep my sanity through all of this. iii TABLE OF CONTENTS ABSTRACT ................................................................................................................................................................II ACKNOWLEDGEMENTS .....................................................................................................................................III TABLE OF CONTENTS ......................................................................................................................................... IV LIST OF FIGURES.................................................................................................................................................VII LIST OF TABLES.................................................................................................................................................... IX CHAPTER 1: INTRODUCTION TO TRAUMATIC EYE INJURIES, CURRENT METHODS OF DETERMINING EYE INJURY POTENTIAL, AND GOALS OF RESEARCH .................................................1 INTRODUCTION ..........................................................................................................................................................1 EYE ANATOMY ..........................................................................................................................................................1 EYE INJURY TYPES ....................................................................................................................................................3 CIVILIAN EYE INJURIES .............................................................................................................................................4 MILITARY EYE INJURIES............................................................................................................................................6 BENEFITS OF EYE PROTECTION..................................................................................................................................9 ATD HEADFORMS ...................................................................................................................................................12 FOCUS HEADFORM ................................................................................................................................................14 CONCLUSION ...........................................................................................................................................................18 RESEARCH OBJECTIVES ...........................................................................................................................................19 REFERENCES............................................................................................................................................................20 CHAPTER 2: THE EFFECTS OF THE EXTRAOCULAR MUSCLES ON EYE INJURY BIOMECHANICS.....................................................................................................................................................22 ABSTRACT ...............................................................................................................................................................22 INTRODUCTION ........................................................................................................................................................22 METHODOLOGY.......................................................................................................................................................24 RESULTS..................................................................................................................................................................26 DISCUSSION .............................................................................................................................................................29 CONCLUSION ...........................................................................................................................................................31 REFERENCES............................................................................................................................................................31