Comparison of Corneal Biomechanical Characteristics After Surface Ablation Refractive Surgery and Novel Lamellar Refractive Surgery PDF Download
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Languages : en
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Author: C.J. Roberts
Publisher: Kugler Publications
ISBN: 9062998763
Category : Medical
Languages : en
Pages : 328
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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.
Author: Fabio A. Guarnieri
Publisher: Springer
ISBN: 1493917676
Category : Medical
Languages : en
Pages : 151
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Book Description
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.
Author: Jeewan S Titiyal
Publisher: Jaypee Brothers Medical Publishers
ISBN: 9354652131
Category : Medical
Languages : en
Pages : 267
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Book Description
Refractive surgery is eye surgery to improve the refractive state of the eye and reduce or eliminate the need for glasses or contact lenses. The most common type of refractive surgery uses lasers to reshape the curvature of the cornea. This book is a practical guide to the latest advances in refractive surgery procedures. Beginning with an introduction to the evolution of refractive surgery, the next section discusses pre-operative workup, patient evaluation, and decision making. The following sections cover different refractive procedures including corneal ablative, refractive lenticule extraction, lens-based surgeries, enhancements and retreatments, and presbyopia (a condition associated with aging). The final section covers a selection of miscellaneous topics such as bioptics, collagen cross-linking, intracorneal ring segments, incisional surgery, and challenging scenarios. Each section is highly illustrated and provides in depth detail on machines and laser platforms, surgical techniques, outcomes, and potential complications and their management. Key points Practical guide to latest advances in refractive surgery Covers numerous different procedures In depth detail on techniques, outcomes, equipment and complications Highly illustrated with clinical photographs and figures
Author: Dimitri T. Azar
Publisher: Elsevier Health Sciences
ISBN: 0323551165
Category : Medical
Languages : en
Pages : 608
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Book Description
Comprehensive and clinically focused, Refractive Surgery, 3rd Edition, brings you the knowledge and expertise of leading ophthalmology experts and refractive surgeons from around the world. Together they provide practical coverage of the latest advances in this fast-changing field, including improved optics and biomechanics, improved diagnostics, new surgical techniques, and more. Hundreds of high-quality photographs guide you from patient selection to mastery of surgical techniques. Offers step-by-step guidance on a wide range of common refractive procedures. Covers new topics such as management of LASIK complications; SMILE and management of SMILE complications; collagen cross-linking, including instrumentation and applications in keratoconus and ectasia; intracorneal lenses; and multifocal and accommodating IOLs. Contains a new chapter on Preoperative Evaluation of Keratoconus and Ectasia. Uses high-quality surgical video clips to demonstrate a variety of surgical techniques. Addresses initial as well as ongoing management of patients. Includes tables of indications, preferences, hot tips, and management of complications throughout, making guidance quick and easy to access.
Author: Edmund Tsui
Publisher: Springer Nature
ISBN: 9819916615
Category : Medical
Languages : en
Pages : 364
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Book Description
The book discusses innovations in surgical techniques and procedures in multiple ophthalmic subspecialties with an evidence based approach.With the rapid development of the field of ophthalmology over the last 10 years, from the development of ever more sophisticated ocular diagnostic technology, to the development of novel medical therapies, ophthalmologists have seen dramatic advancements in the care of their patients.The book highlights various ophthalmic surgical techniques that have been devised, modified, and refined over the last decade, allowing ophthalmic surgeons to achieve surgical perfection. It includes illustrations, clinical photos, videos of surgical procedure. It includes easy to follow salient points in each chapter.This volume of the Current Practices in Ophthalmology book series serves as a valuable resource for post graduate residents in ophthalmology, practicing ophthalmologists, subspecialty fellows, vision science researchers, and general ophthalmologists.
Author: Dan Reinstein
Publisher: CRC Press
ISBN: 1040136915
Category : Medical
Languages : en
Pages : 720
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Book Description
Corneal refractive surgeons are likely already familiar with the theory behind small incision lenticule extraction (SMILE) and the excellent postoperative outcomes it can achieve, but they were left without a thorough and comprehensive guide to performing the procedure, until now. The Surgeon’s Guide to SMILE: Small Incision Lenticule Extraction is designed to provide surgeons who are interested in starting or are already performing SMILE with a detailed description of the preoperative assessment, surgical technique, and postoperative management of SMILE treatments. This book by Professor Dan Z. Reinstein, Mr. Timothy J. Archer, and Dr. Glenn I. Carp is designed as a surgical video-fellowship, focusing on the granular details of every aspect of patient preparation and management with special attention to how to perform a perfect routine SMILE procedure. The protocols and methods are sourced in both the published scientific evidence and the extensive experience and expertise of the authors. It also includes tips and tricks of how to manage the full range of possible scenarios and complications that can occur during and after a SMILE surgery. Each process described in the book is accompanied by at least one, and in many cases numerous, narrated video examples. Bonus! This dynamic learning tool is supplemented by the SMILE video library containing over 16 hours of surgical videos and tutorials hosted on a companion website. The succinct and demonstrative style of The Surgeon’s Guide to SMILE: Small Incision Lenticule Extraction will help novice and experienced SMILE surgeons alike learn important techniques and improve their outcomes. From the Foreword: “The reader is in for a treat, receiving authoritative technical information from seasoned leaders in the field of refractive surgery, who have attained tremendous experience in excimer laser ablation and who have also been on the forefront of scientific evaluation of the new femtosecond only surgical approach that is SMILE.” -J. Bradley Randleman, MD, University of Southern California, Los Angeles, CA
Author: John Charles Casebeer
Publisher:
ISBN:
Category : Science
Languages : en
Pages : 220
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Book Description
In this book, Drs. Casebeer, Ruiz, & Slade go beyond the principles of their own techniques of ALK & LASIK to outline & define the foundation of how these procedures were developed & how they should be performed today. The text closes with a comprehensive look at the ALK & LASIK study results that are available, including the ALK Prospective Trial, the Jeddah ALK Retrospective Review, the Buratto et al Series, the Brint/Slade Summit MKM Report, the Salah et al Pilot Study, the LASIK with Flap Study by Pallikaris & Siganos, & the Bogota LASIK Prospective Study.
Author: Sujata Das
Publisher: Springer Nature
ISBN: 9811942625
Category : Medical
Languages : en
Pages : 298
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Book Description
The book covers various aspects of the management of keratoconus, which is a leading cause of visual impairment in young adults. It focuses on the epidemiology and risk factors of keratoconus with a special focus on Southeast Asia. Keratoconus affects the quality of vision, thereby affecting the quality of life. While most patients present with defective vision, many are diagnosed accidentally during screening for refractive surgery. The book covers the varied epidemiology of keratoconus across different parts of the world. It discusses many systemic and ocular diseases associated with keratoconus. The book covers the newer diagnostic techniques and various treatment procedures for keratoconus, helping in diagnosing keratoconus in the early stages and closely watching the progression. It discusses various contact lenses to improve vision quality; widely used collagen crosslinking, and its various modifications for halting the progression. It also explains the surgical approach for keratoconus, such as penetrating keratoplasty, lamellar keratoplasty and other lens-assisted procedures. The book is relevant for general ophthalmologists and cornea specialists.
Author: Melanie Corbett
Publisher: Springer
ISBN: 3030106969
Category : Medical
Languages : en
Pages : 287
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Book Description
The new edition of this leading text atlas on corneal topography has been updated to include the latest advances in technology, such as Pentacam and Orbscan. The principles and theory underlying each technology are first clearly explained, and clinical applications are then examined. The authors describe how to use the different technologies and devices, explain the clinical readout with illustrations of normal corneal topography, discuss applications and findings in common disease states, and present the appearances after various corneal surgical procedures. The pros and cons of each system are highlighted. This up-to-date, superbly illustrated book is the most comprehensive guide to corneal topography currently available. It is anticipated that this second edition will become the seminal corneal topography textbook for all with an interest in corneal disease and its management, and refractive surgery.
