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Understanding Corneal Biomechanics Through Experimental Assessment and Numerical Simulation

Understanding Corneal Biomechanics Through Experimental Assessment and Numerical Simulation PDF Author: Ahmed Elsheikh
Publisher:
ISBN: 9781536112207
Category : MEDICAL
Languages : en
Pages : 63

Book Description


Understanding Corneal Biomechanics Through Experimental Assessment and Numerical Simulation

Understanding Corneal Biomechanics Through Experimental Assessment and Numerical Simulation PDF Author: Ahmed Elsheikh
Publisher:
ISBN: 9781536112207
Category : MEDICAL
Languages : en
Pages : 63

Book Description


Corneal Biomechanics

Corneal Biomechanics PDF Author: C.J. Roberts
Publisher: Kugler Publications
ISBN: 9062998763
Category : Medical
Languages : en
Pages : 328

Book Description
While lecturing in recent months at a number of prominent institutions, I asked some of the residents and fellows whether and how they might benefit from a book on corneal biomechanics. The typical response was the look of a deer caught in the headlights as they tried to intuit the “appropriate” answer, but had little understanding or insight as to why this would be an important and useful knowledge base for them now, or in the future. I then posed the question differently. “Would a book that explained corneal biomechanical principles and testing devices and their application in detecting eyes at risk for developing keratoconus and post-LASIK ectasia, understanding the biomechanical impact of specific types of keratorefractive surgery and riboflavin UV-A corneal collagen cross-linking, and the impact of corneal biomechanics on the fidelity of intraocular pressure measurement and risk for glaucoma progression be of interest?” Framed in this context, the answer I got was a resounding, “Yes!” Therein lies a fundamental disconnect that highlights both the opportunity and need to educate all ophthalmologists about this nascent field. This comprehensive book is strengthened by the breadth of contributions from leading experts around the world and provides an important resource for ophthalmologists at all levels of training and experience. It gives a panoramic snapshot of our understanding of corneal biomechanics today, bridging the gap between theoretical principles, testing devices that are commercially available and in development as well as current and potential future clinical applications. While there has been a long-held appreciation that all types of keratorefractive surgery have an impact and interdependence on corneal biomechanics and wound healing, the initial finite element analyses that were applied to understand radial keratotomy were limited by incorrect assumptions that the cornea was a linear, elastic, homogenous, isotropic material.1 With the advent of excimer laser vision correction, critical observations indicated that Munnerlyn’s theoretic ablation profiles did not account for either lower or higher order (e.g. spherical aberration) refractive outcomes,2 suggesting that there were important components missing from the equation—e.g., corneal biomechanics and wound healing. In a seminal editorial, Roberts3 pointed out that the cornea is not a piece of plastic, but rather a material with viscoelastic qualities. Since that time, much has been learned about spatial and depth- related patterns of collagen orientation and interweaving, as well as the biomechanical response to different keratorefractive surgeries that sever tension-bearing lamellae, as the cornea responds to and redistributes stress induced by IOP, hydration, eye rubbing, blinking and extraocular muscle forces.3-6 The first reports of post-LASIK ectasia7 highlighted the need to identify a biomechanical signature of early keratoconus as well as corneas at high risk of developing ectasia irrespective of their current topography or tomography. The introduction of two instruments into clinical use—the Ocular Response Analyzer (ORA) and the Corneal Visualization Scheimpflug Technology (Corvis ST)—that allow measurement of various biomechanical metrics further catapulted the field. The availability of these instruments in routine clinical settings allowed the systematic study of the effect of age, collagen disorders, collagen cross-linking, corneal rings, flaps of various depths, contour, sidecut angulation, pockets, and flockets, just to name of few. Future application of biomechanics to the sclera may improve our understanding of the development and prevention of myopia, as well as scleral surgeries and treatments under development for presbyopia. It was appreciated by Goldmann and Schmidt that corneal thickness and curvature would influence the measurement of applanation tonometry. The recent ability to measure some corneal biomechanical metrics have led to IOP measurement that may be more immune both to their influence and the impact of central corneal thickness (CCT). Certain chapters in this book explain how a thin cornea could be stiffer than a thick one and that stiffness is also impacted by IOP, thereby precluding simplistic attempts to adjust IOP measurements using nomograms based upon CCT alone. Also highlighted is how corneal hysteresis, the ability of the cornea to absorb and dissipate energy during the bidirectional applanation response to a linear Gaussian air puff, appears to be an independent risk factor for glaucoma progression and rate of progression.9,10 This comprehensive book starts out with a section devoted to outlining basic biomechanical principles and theories, teaching us the language of what Dupps11 has referred to as “mechanospeak”, thus providing a context and common vocabulary to better comprehend the following chapters. By first defining basic concepts such as stress-strain relationships and creep, this theoretical basis is later applied to explain the pathogenesis of corneal diseases, e.g., explaining how a focal abnormality in corneal biomechanical properties precipitates a cycle of decompensation and localized thinning and steepening, clinically expressed as ectasia progression. These early chapters further detail biomechanical differences between in-vivo and ex-vivo testing, between human and animal corneas and sclera, and between methods of testing. The second section provides a thorough description of two FDA-approved devices to measure corneal biomechanics in the clinic (i.e., the ORA and the Corvis ST), as well as an overview of potential future technologies, including OCT with air puff stimulus, ocular pulse elastography, and Brilloiun microscopy. The third and final section of the book is a thorough treatise on how to interpret the metrics derived from the waveform provided by available clinical devices; their adjunct use in ectasia risk screening; the comparative biomechanical impact of various keratorefractive surgeries and corneal procedures such as PRK, LASIK, SMILE, and corneal collagen cross-linking; the impact of corneal biomechanics on IOP measurement; and potential biomechanical markers of enhanced susceptibility to glaucoma progression. This compendium of our current knowledge of corneal biomechanics, its measurement and application, provides a strong foundation to more fully understand advances in keratorefractive and corneal surgery, diseases, and treatments, all of which are interdependent on and influence inherent corneal biomechanical properties and behavior. Both the robust aspects and limitations of our current understanding are presented, including the challenge of creating accurate and predictive finite element models that incorporate the impact of IOP, corneal thickness, geometry, and scleral properties on corneal biomechanics. This book provides a key allowing clinical ophthalmologists and researchers to grasp the basics and nuances of this exciting field and to shape it as it evolves in the future.

Biomechanics of the Eye

Biomechanics of the Eye PDF Author: Cynthia J. Roberts
Publisher: Kugler Publications
ISBN: 9062998860
Category : Medical
Languages : en
Pages : 546

Book Description
Covering all major components of the ocular system, this state-of-the-art text is essential for vision scientists, biomedical engineers, and advanced clinicians with an interest in the role of mechanics in ocular function, disease, therapeutics, and surgery. With every chapter, leading experts strengthen the arguments that biomechanics is an indispensable and rapidly evolving tool for understanding and managing ocular disease.

50+ Years of AIMETA

50+ Years of AIMETA PDF Author: Giuseppe Rega
Publisher: Springer Nature
ISBN: 3030941957
Category : Technology & Engineering
Languages : en
Pages : 505

Book Description
The book retraces the history of the Italian Association of Theoretical and Applied Mechanics (AIMETA) since its establishment in 1965. AIMETA is the official Italian association of mechanics adhering to IUTAM (International Union of Theoretical and Applied Mechanics), which organizes and coordinates a meaningful number of research activities, the most important of which are the biennial National Congress and the internationally renowned journal “Meccanica”, published by Springer. Besides collecting and organizing all related important data and information, as far as possible, by distinguishing among the five scientific areas – general mechanics, solids, structures, fluids, machines – encompassed by AIMETA, the history of the association is assumed as a proper perspective to overview the evolution of theoretical and applied mechanics in Italy over about the last fifty years. This is accomplished in the first part of the book. with also a specific focus on the mechanics of solids and structures, where the biographies of a meaningful number of recognized Italian scholars of mechanics in all areas are also provided, along with testimonials and memories by a few senior people meaningfully involved with AIMETA and Italian mechanics. The second part gives an account, although unavoidably incomplete, of recent developments of mechanical sciences in Italy, as reflected also in the activities of AIMETA and with reference to the international context. Contributions by a number of invited senior scholars, still very active, consist of overviews on some scientific themes in the various areas, summaries of achievements of research groups, expressions of research viewpoints, prospects for future developments.

Biomedical Simulation

Biomedical Simulation PDF Author: Fernando Bello
Publisher: Springer Science & Business Media
ISBN: 3540705201
Category : Computers
Languages : en
Pages : 238

Book Description
This book constitutes the refereed proceedings of the 4th International Symposium on Biomedical Simulation, ISBMS 2008, held in London, UK, in July 2008. The 19 revised full papers and 7 poster papers presented were carefully reviewed and selected from numerous submissions. The papers are organized in four different sections corresponding to key areas and techniques of this constantly expanding field: finite element modeling, mass spring and statistical shape modeling, motion and fluid modeling and implementation issues. An additional section covers the posters presented at the meeting.

Seventh International Technical Conference on Experimental Safety Vehicles

Seventh International Technical Conference on Experimental Safety Vehicles PDF Author:
Publisher:
ISBN:
Category : Automobiles
Languages : en
Pages : 992

Book Description


How Can Corneal Biomechanics Help with Clinical Applications?

How Can Corneal Biomechanics Help with Clinical Applications? PDF Author: FangJun Bao
Publisher: Frontiers Media SA
ISBN: 2832522572
Category : Science
Languages : en
Pages : 124

Book Description


Report - International Technical Conference on Experimental Safety Vehicles

Report - International Technical Conference on Experimental Safety Vehicles PDF Author:
Publisher:
ISBN:
Category : Automobiles
Languages : en
Pages : 1366

Book Description


Encyclopedia of Modern Optics

Encyclopedia of Modern Optics PDF Author: Bob D. Guenther
Publisher: Academic Press
ISBN: 0128149825
Category : Technology & Engineering
Languages : en
Pages : 2253

Book Description
The Encyclopedia of Modern Optics, Second Edition, Five Volume Set provides a wide-ranging overview of the field, comprising authoritative reference articles for undergraduate and postgraduate students and those researching outside their area of expertise. Topics covered include classical and quantum optics, lasers, optical fibers and optical fiber systems, optical materials and light-emitting diodes (LEDs). Articles cover all subfields of optical physics and engineering, such as electro-optical design of modulators and detectors. This update contains contributions from international experts who discuss topics such as nano-photonics and plasmonics, optical interconnects, photonic crystals and 2D materials, such as graphene or holy fibers. Other topics of note include solar energy, high efficiency LED’s and their use in illumination, orbital angular momentum, quantum optics and information, metamaterials and transformation optics, high power fiber and UV fiber lasers, random lasers and bio-imaging. Addresses recent developments in the field and integrates concepts from fundamental physics with applications for manufacturing and engineering/design Provides a broad and interdisciplinary coverage of specialist areas Ensures that the material is appropriate for new researchers and those working in a new sub-field, as well as those in industry Thematically arranged and alphabetically indexed, with cross-references added to facilitate ease-of-use

Ocular Biomechanics in Health and Pathophysiology

Ocular Biomechanics in Health and Pathophysiology PDF Author: Matthew A. Reilly
Publisher: Frontiers Media SA
ISBN: 2832550398
Category : Technology & Engineering
Languages : en
Pages : 187

Book Description
Biomechanical mechanisms may contribute to a large number of visual processes and pathologies, including glaucoma, keratoconus, refractive surgery, accommodation, presbyopia, myopia, hyperopia, trauma, retinal detachment, ocular development, vitreous substitution, cataract surgery, corneal transplant, and many others. Departures from homeostatic loading may drive a large number of these processes in ways we are only beginning to recognize. This Research Topic will explore how ocular biomechanics contribute to both the homeostasis and pathophysiology of the eye and visual system. It is generally unknown whether changes in load drive changes in biomechanical properties or vice versa. Clarifying driving forces for disease and elucidating the pathophysiologic response will ultimately enable the development of targeted treatments for many ocular and visual diseases for which biomechanics plays a role.