Download or read book Corneal Biomechanics written by C.J. Roberts and published by Kugler Publications. This book was released on 2017-05-15 with total page 328 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book Corneal Biomechanics and Refractive Surgery written by Fabio A. Guarnieri and published by Springer. This book was released on 2014-11-27 with total page 151 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents a unique approach not found in any other text for those looking to improve the clinical results of refractive surgery by gaining a better understanding of corneal biomechanics and the instrumentation related to it. Written by leading experts in the field, this book provides authoritative coverage of the interactions of the cornea and the bioinstrumentation, such as corneal topography, pachymetry, aberrometers, tonometry and optical coherence tomography. Organized in an easy-to-read manner, Corneal Biomechanics and Refractive Surgery is designed for refractive surgeons and general ophthalmologists alike and describes the biomechanical role of the corneal tissue and how each part is affected in refractive surgery. Additionally, showing what the bioinstrumentation can measure, how models can improve understanding of the interaction between biomechanics, bioinstrumentation, and refractive surgery, and how these models and bioinstrumentation together can improve the refractive results, are also discussed.
Download or read book Biomechanics of the Eye written by Cynthia J. Roberts and published by Kugler Publications. This book was released on 2018-04-20 with total page 546 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book Understanding Corneal Biomechanics Through Experimental Assessment and Numerical Simulation written by Ahmed Elsheikh and published by . This book was released on 2010 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Ocular Biomechanics Group was established in 2002 with one clear target; to develop a virtual reality model of the human eye that can be used effectively and reliably to predict ocular response to surgery, injury and disease. This ambitious, and seemingly illusive, target helped plan our activities over the last 6 years and will still be focusing our efforts as we strive to create the necessary knowledge using experimental methods, build the predictive tools using programming and analysis means, and validate the findings in both the laboratory and the clinic. This book presents an overview of our biomechanical studies from laboratory material characterisation to finite element numerical simulation. The chapter describes what has been achieved and points at the remaining gaps in our knowledge. It explains that while much remains unknown in ocular behaviour, we are now in a good position to use available knowledge to progress predictive modelling and use it in actual applications such as improving the accuracy of tonometry techniques, planning of refractive surgeries and design of contact lenses. The discussion focuses on the cornea, although scleral biomechanics receive some mention. The chapter also refers to microstructural, biomechanical and topographic studies conducted by other research groups. Coverage of these studies has been necessary to provide a more complete image of current understanding of corneal biomechanics.
Download or read book Ocular Rigidity Biomechanics and Hydrodynamics of the Eye written by Ioannis Pallikaris and published by Springer Nature. This book was released on 2021-05-26 with total page 359 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book focuses on the concept of ocular rigidity, the biomechanical properties and hydrodynamics of the human eye. The basics of anatomy and physiology are explored and the relevant data for the clinician are emphasized throughout the book. The engineering aspects as well as the clinical interpretation are presented to provide context. Ocular Rigidity, Biomechanics and Hydrodynamics of the Eye summarises recent evidence on ocular rigidity, but also provides a complete presentation of the data so far. The authors have recently worked on ocular rigidity corneal and globe biomechanics and hydrodynamics and the new, up-to-date data on the subject are highlighted in each chapter. The aim is to provide the framework or the understanding of these parameters and to determine their relevance in health and disease. This book will be an essential read for all practicing ophthalmologists looking to gain a more in-depth understanding of this interesting area of research particularly in refractive surgery and glaucoma.
Download or read book How Can Corneal Biomechanics Help with Clinical Applications written by FangJun Bao and published by Frontiers Media SA. This book was released on 2023-05-03 with total page 124 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Diagnostics in Ocular Imaging written by Mehrdad Mohammadpour and published by Springer Nature. This book was released on 2020-11-13 with total page 743 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents a new avenue in the field of ophthalmology and sheds light on the field of eye imaging. With the increasing availability of electronic devices and their important role in both personal and professional aspects of human life, there is a growing need for perfect vision. Ophthalmic imaging is a major tool for screening and documenting eye diseases in both medical and surgical fields of ophthalmology and is also of use for ophthalmologists around the globe. The number of eye-imaging devices has increased dramatically, however undiagnosed or poorly managed eye diseases remain a significant cause of ocular and visual problems worldwide. This essential guide addresses the need for a book that is dedicated to ophthalmic imaging, covering the cornea, glaucoma, retina and orbital imaging with updates on medical and surgical aspects of the topic.
Download or read book New Frontiers for the Treatment of Keratoconus written by César Carriazo and published by Springer Nature. This book was released on 2021-04-01 with total page 145 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book updates the reader about the latest bio-mechanical concepts underlying keratoconus diagnosis and the various treatment alternatives: from conventional alternatives with a real cost/benefit description, to some innovative alternatives that have come to the fore in recent years. It discusses the latest software and technology utilized in keratoconus diagnosis as well as the more innovative surgical techniques used to treat keratoconus. New Frontiers for the Treatment of Keratoconus represents an essential book for ophthalmologists and specialists in cornea and refractive surgery who are looking to position themselves at the forefront of the diagnosis and treatment of keratoconus.
Download or read book Development and Application of Optical Coherence Elastography for Corneal Biomechanics written by Matthew R Ford and published by . This book was released on 2015 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The biomechanical properties of the cornea are an important determinant of both the shape and function of the human visual system. Measuring the biomechanical properties on an in vivo basis requires the development of technologies not typically associated with mechanical measurement. Optical Coherence Elastography (OCE) is an optical based measurement capable of measuring micron level displacements in accessible tissues. The application of OCE to corneal measurement was made possible by the use of speckle tracking in the corneal stroma. Application of OCE to human donor corneas was used to measure the biomechanical properties of the human cornea in three separate states: edematous, normal or deturgessed, and post crosslinking (CXL). The corneal mechanical properties were shown to increase in stiffness in each of the three states, from least stiff when edematous to most stiff post CXL. The early stages of the development of Doppler Shear Wave Optical Coherence Elastography to measure mechanical properties without the need for additional modeling and inferences. The technique utilizes the Doppler shift of a shear wave as it is scanned by OCE to measure the Shear Modulus and Young's modulus of the tissue. As a technique that can be performed on a single two dimensional scan of the tissue, it is suitable for high speed in vivo use. OCE provides a promising tool for measuring the biomechanical properties of the cornea under in vivo conditions.
Download or read book Corneal Surgery written by Frederick S. Brightbill and published by Elsevier Health Sciences. This book was released on 2009-01-01 with total page 970 pages. Available in PDF, EPUB and Kindle. Book excerpt: Part. 1 Introduction to corneal function and surgery -- Part. 2 Testing and measuring corneal function -- Part. 3 Ocular surface surgery and reconstruction -- Part. 4 Techniques in corneal transplantation -- Part. 5 Special situations in corneal surgery -- Part. 6 Surgical correction of refractive errors.
Download or read book Ocular Biomechanics in Health and Pathophysiology written by Matthew A. Reilly and published by Frontiers Media SA. This book was released on 2024-06-13 with total page 187 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book Irregular Astigmatism written by Tracy Schroeder Swartz and published by SLACK Incorporated. This book was released on 2008 with total page 326 pages. Available in PDF, EPUB and Kindle. Book excerpt: Since the advent of keratorefractive surgery and its rising popularity, irregular astigmatism has become an increasingly important issue for ophthalmologists and optometrists. Despite the success of LASIK and PRK, there are more and more patients experiencing visual quality problems due to the non-physiological modification of the corneal structure. Among these complications, irregular astigmatism is perhaps the most difficult to treat. Every physician who performs keratorefractive surgery understands that in reducing a patient.s refractive error, there is a possibility of creating irreversible effects on visual quality. This text is intended to help prevent and reduce the iatrogenic creation of irregular astigmatism, as well as provide effective treatment when postoperative complications do arise. With the maturation of keratorefractive technology in recent years, effective treatment for iatrogenic irregular astigmatism is quickly developing. It provides everything refractive surgeons, ophthalmologists, and optometrists need to know about this important topic.
Download or read book Biomechanics written by and published by BoD – Books on Demand. This book was released on 2019-01-30 with total page 114 pages. Available in PDF, EPUB and Kindle. Book excerpt: I have taught a variety of courses in biomechanics, introductory and advanced, at multiple universities in Canada. I have not been able to find or use an appropriate textbook for students whose background is not biomedical engineering. It should be noted that there are many outstanding books on biomechanics; however, they are usually not very introductory or the topics covered are too detailed, which makes it impossible for those audiences to make effective use of the book. The present book is an attempt to fill this gap. No previous familiarity of anatomy, biology, or physiology is expected, and in fact every chapter begins with a review of the relevant necessary background. Each chapter then highlights identification and explanation of the indispensable aspects of the associated biomechanics issues.
Download or read book Characterization of Corneal Biomechanical Properties Using Experimental and Computational Methods written by Xiaoyin He and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: Cornea, the clear front part of the eye, opens a window for ocular examination. The importance of corneal biomechanics in the normal and pathological functions of the eye has gained its credibility in the past decades. The goal of our research is to better understand the potential role of ocular tissue biomechanical properties in the assessment of the ocular diseases. Specifically, we investigated roles of the corneal biomechanical properties in response to intraocular loading and the methods for non-invasive evaluation of corneal biomechanical properties.
Download or read book Advances in Biomechanics and Tissue Regeneration written by Mohamed H. Doweidar and published by Academic Press. This book was released on 2019-08-13 with total page 436 pages. Available in PDF, EPUB and Kindle. Book excerpt: Advances in Biomechanics and Tissue Regeneration covers a wide range of recent development and advances in the fields of biomechanics and tissue regeneration. It includes computational simulation, soft tissues, microfluidics, the cardiovascular system, experimental methods in biomechanics, mechanobiology and tissue regeneration. The state-of-the-art, theories and application are presented, making this book ideal for anyone who is deciding which direction to take their future research in this field. In addition, it is ideal for everyone who is exploring new fields or currently working on an interdisciplinary project in tissue biomechanics. - Combines new trends in biomechanical modelling and tissue regeneration - Offers a broad scope, covering the entire field of tissue biomechanics - Contains perspectives from engineering, medicine and biology, thus giving a holistic view of the field
Download or read book Corneal Biomechanics written by Cynthia Roberts and published by . This book was released on 2005 with total page 245 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Intraocular and Intracranial Pressure Gradient in Glaucoma written by Ningli Wang and published by Springer. This book was released on 2019-03-30 with total page 321 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book focuses on the characteristic of glaucomatous optic neuropathy and its relationship with cerebrospinal fluid (CSF) pressure. It also explores the potential novel methods to manage glaucoma by adjusting CSF pressure. This book covers several interesting topics such as why normal tension glaucoma (NTG) patients still develops into glaucoma without high intraocular pressure (IOP); and whether there are factors other than IOP contributing to the pathogenesis of NTG why the role of IOP in the pathogenesis of POAG becomes vague and controversial. This book contains over 40 chapters, including numerous images from clinical patients and experiments on gross anatomy, pathological tissue, and immunohistochemistry, electronic speculum etc. The ophthalmologists and researchers can also benefit from the clinical cases. We hope this book serves as a clinical guidance with practical significant for the understanding, prevention and diagnosis of glaucoma.
