Based on Dr. Wrighta (TM)s classic major reference, Handbook of Pediatric Eye and Systemic Disease outlines the latest findings in diagnosing children's eye diseases and their treatment options. Distilling the essentials of ocular manifestations of systemic disorders and diseases into a portable, complete and authoritative pocket reference, this handbook offers a complete picture of how to best treat pediatric patients. Specifically, the introductory chapters on the specifics of pediatric ophthalmology (embryology, post-natal development and the pediatric exam) will help newcomers to pediatric practice fully grasp the subtle differences in pediatric care. The chapters are written by leading experts in the field and are presented in a user-friendly format, relying on heavily illustrated color plates, clinically helpful tables, charts, and decision-making guidelines. This approach will enable the practitioner (whether specialist or generalist) to make the most accurate diagnosis and choose the most effective treatment option.

Based on Dr. Wrighta (TM)s classic major reference, Handbook of Pediatric Neuroophthalmology outlines the latest findings in diagnosing children's eye diseases and their treatment options. Distilling the essentials of ocular manifestations of pediatric neuroophthalmologic disorders and diseases into a portable, complete and authoritative pocket reference, this handbook offers a complete picture of how to best treat pediatric patients. Specifically, the introductory chapters on the specifics of pediatric ophthalmology (embryology, post-natal development and the pediatric exam) will help newcomers to pediatric practice fully grasp the subtle differences in pediatric care. The chapters are written by leading experts in the field and are presented in a user-friendly format, relying on heavily illustrated in color plates, clinically helpful tables, charts, and decision-making guidelines. This approach will enable the practitioner (whether specialist or generalist) to make the most accurate diagnosis and choose the most effective treatment option.

Updated to include new material for beginners in ophthalmology and optometry," Ocular Anatomy and Physiology, Second Edition "is an essential text that covers a range of fundamental information for students and clinicians.
With collaborations from Al Lens, Sheila Coyne Nemeth, and Janice K. Ledford, "Ocular Anatomy and Physiology, Second Edition "now begins with a jump-start chapter to overview the topic for those new to the field of eye care. Chapter two delves into embryology--a topic rarely covered--and addresses each structure of the eye, including the bony orbit, eyebrows, eye lids, lacrimal system, extraocular muscles, and the globe.
While the text continues to emphasize normal anatomy, each chapter contains a glossary of common disorders. Also included is a description of diagnostic methods for examining various tissues. The physiology of various structures and systems is explained, including the visual pathway, the inflammatory response, immunology, binocular vision, refractive errors, and accommodation. To enhance the reader's understanding of each topic, illustrations are provided.
Features of the Second Edition:
- New jump-start chapter for beginners
- Details on diagnostic methods for each structure or segment, including optical coherence tomography and retinal thickness analysis
- Glossary of common disorders at the end of each chapter
With new features and information, "Ocular Anatomy and Physiology, Second Edition" is a valuable text for ophthalmic and optometric assistants, training facilities, and practices, as well as beginners in the field of eye care, including sales representatives and pre-med students.

The growth of new drugs entering the practice of ophthalmology requires both the resident and established ophthalmologist to understand and accurately prescribe the new pharmacologic armamentarium. This excellent handbook a ~Drugs in Ophthalmologya (TM) contains drug information compiled by experts from the United States (Kaiser Permanente and Jules Stein Eye Institute/ UCLA) and Europe (University of Vienna). It is concise, well-structured and easy to use. With separate sections for antibiotics, antivirals, antifungals, anesthetics and immunosuppressants, it provides following subsections for each drug: Class of the drug, Indications, Dosage, Contraindications, Warnings, Adverse reactions, Drug interactions. Practitioners may want to have multiple copies of the book for easy reference.

Clearly organized and simply presented, "The Low Vision Handbook for Eyecare Professionals, Second Edition" offers an introduction to all aspects of low vision, including a short history of low vision and the basic optics of magnifiers.
Updated and revised this second edition of "The Low Vision Handbook for Eyecare Professionals" provides practical material on assessing low vision patients, the psychology of visual loss, and ways to alleviate patients' common fears. Additionally, Barbara Brown explores current optical, nonoptical, and electronic devices and their appropriate uses for various patients.
Additional features include:
- Case histories to explain some differences among patients at varying levels of vision loss
- Key points and study icons that highlight topics of interest for paraprofessionals studying for their certification exams
- Addresses and websites for vendors of low vision aids and devices
- Contact information for rehabilitation centers and support agencies to benefit visually impaired patients
- Multiple references and resources for further study
"The Low Vision Handbook for Eyecare Professionals, Second Edition" is perfect for students of the ophthalmic and optometric sciences, introductory-level assistants and other medical office staff, as well as more experienced technicians. The easy-to-read format, user-friendly terminology, and resource information make it an invaluable book for all who assist low vision patients.

For those who are new to the subject, ocular pharmacology can be a difficult and sometimes overwhelming topic.  Ophthalmic Medications and Pharmacology, Second Edition is a reader-friendly guide that provides a quick review and basic clinical reference of ocular pharmacology.   In this updated and revised second edition, Drs. Duvall and Kershner present an overview to the medication and drugs found most commonly in ophthalmic practice without overwhelming those professionals new to the subject.    Ophthalmic Medications and Pharmacology concisely reviews commonly used and prescribed medications, how they work, dosage, therapeutic use, and potential side effects.  This new edition also highlights key information for patients about the medications they encounter and are prescribed in the clinic.   Ophthalmic staff, students, and research professionals looking for an introduction and basic go-to guide will welcome having a copy of Ophthalmic Medications and Pharmacology by their side. New to this edition: ·        An appendix focused on the drug approval process. ·        A chapter on retinal therapies. ·        Study icons to assist in the learning process. ·        New coverage of vasoconstrictors.    

Glaucoma is the second leading cause of blindness globally. Early detection and treatment can prevent its progression to avoid total blindness. This book discusses and reviews current approaches for detection and examines new approaches for diagnosing glaucoma using CAD system. Computer-Aided Glaucoma Diagnosis System, Chapter 1 provides a brief introduction of the disease and current methodology used to diagnose it today. Chapter 2 presents a review of the medical background of the disease, followed by a theoretical and mathematical background used in fundus image processing. Chapter 3 is a literature review about segmentation and feature extraction. Chapter 4 describes the formulation of the proposed methodology. In Chapter 5, the results of optic disc and optic cup segmentation algorithm are presented, the feature extraction and selection method, experimental results and performance evaluations of the classifier are given. Chapter 6 presents the conclusions and discussion of the future potential for the diagnostic system. This book is intended for biomedical engineers, computer science students, ophthalmologists and radiologists looking to develop a reliable automated computer-aided diagnosis system (CAD) for detecting glaucoma and improve diagnosis of the disease. Key Features Discusses a reliable automated computer-aided diagnosis system (CAD) for detecting glaucoma and presents an algorithm that detects optic disc and optic cup Assists ophthalmologists and researchers to test a new diagnostic method that reduces the effort and time of the doctors and cost to the patients Discusses techniques to reduce human error and minimize the miss detection rate and facilitate early diagnosis and treatment Presents algorithms to detect cup and disc color, shape features and RNFL texture features Dr. Arwa Ahmed Gasm Elseid is an assistant professor, Department of Biomedical Engineering, Sudan University of Science and Technology, Khartoum, Sudan. Dr. Alnazier Osman Mohammed Hamza is professor of Medical Imaging, College of Engineering, Sudan University of Sciences and Technology, Khartoum, Sudan.

"The Eye Exam: A Complete Guide" is a handy reference with a primary focus on developing history and exam skills for all professionals working with patients in the eye clinic. Written in an easy and practical format, "The Eye Exam "presents the proper way to perform a history and physical examination on an eye patient. The opening chapters will educate the reader on how to perform an eye history on adults, as well as special indications and techniques for examining children. Also included are chapters on the foundation of basic optics and how to perform a proper distance and near refraction exams. "The Eye Exam" concludes with how to perform various examination techniques and how to record the findings. Dr. Gary Schwartz includes only the essential information about ophthalmic examinations, so that the reader is not bogged down with unnecessary information about diseases and treatments.

"The Eye Exam "is perfect for the eye clinic novice wanting to learn the basics and be proficient with performing routine eye exams, as well as the experienced clinician looking to enrich existing skills and understanding of the eye exam techniques. Physical Exam Topics Include:

• Subjective and objective refraction
• Near refraction
• Color vision
• Pupil exam
• Motilities
• Alignment
• Slit lamp examination
• Intraocular pressure determination
• Gonioscopy
• Retina examination

Additional features:

• Helpful question and answer sections at the end of most chapters
• Common abbreviations used in the eye clinic
• Eye medications
• Surgical procedures
• A pocket guide of the necessary componentsof the basic eye history and physical exam

Even with the advances in intraocular lens technology and the growing diversity of refractive surgery techniques, the role of contact lenses in ophthalmic practice has only increased. This is due in part to the great strides in materials, technology, expanding applications (both refractive and therapeutic) for contact lenses, and the clear recognition that contact lenses will always be an important tool for the ophthalmologist. With the fitting of contact lenses as a medical art, requiring a thorough understanding of anatomy, physiology adn optics of the eye, this practice is formulaic only in part. The rest of contact lens practice requires sound medical judgment and decision- making that comes only with "hands-on" experience. The authors address this need by starting with a didactic approach that incorporates frequently-asked questions and straightforward answers so that the ophthalmology resident, intermediate contact lens practitioner, and optometrist will find this to be an indispensible resource.

As a draining and secretory system, the nasolacrimal ducts play a role in tear transport and non-specific immune defense. In this book recent advances about the nasolacrimal ducts have been summarized and discussed in context with nasolacrimal duct pathophysiology. 

With an emphasis on the "how and why" of contemporary surgery, Operative Techniques in Surgery, Second Edition, features concise, bulleted text, full-color illustrations, and intraoperative photographs to clarify exactly what to look for and how to proceed. Meticulously edited by Drs. Mary T. Hawn, Aurora D. Pryor, Steven J. Hughes, Michael S. Sabel, Kellie R. Brown and Amy J. Goldberg, this comprehensive, two-volume surgical atlas focuses on the steps of each technique, rapidly directing you to the information you need to choose the right approach for each patient, perform it successfully, and achieve the best possible results. Coverage includes open as well as laparoscopic, robotic, endoscopic, and endovascular procedures in gastrointestinal, thoracic, esophageal, colorectal, hepatobiliary, breast, endocrine, dermatologic, vascular, and trauma surgery New, comprehensive section on trauma surgery, helmed by trauma expert Dr. Amy J. Goldberg New section editors for esophageal and foregut surgery and vascular surgery, Dr. Aurora D. Pryor minimally invasive surgery leader and Kellie R. Brown, expert in vascular surgery. New videos, personally selected by contributing authors and editors, accompany numerous chapters throughout the book Extensive updates throughout, including new coverage of the American Board of Surgery's SCORE Curricula for General Surgery and for Complex General Surgical Oncology Each procedure follows the same format: differential diagnosis, patient history and physical findings, imaging and other diagnostic studies, surgical management, techniques, pearls and pitfalls, postoperative care, outcomes, and complications Enrich Your eBook Reading Experience Read directly on your preferred device(s), such as computer, tablet, or smartphone. Easily convert to audiobook, powering your content with natural language text-to-speech.

An understanding of the fundamental principles of geometrical and physical optics is essential for any student engaged in the study of the visual sciences, but the non-physicist needs a text which clearly explains these notoriously difficult concepts in order to apply them to the practical and clinical aspects of vision. Optics by Freeman and Hull fulfils this requirement admirably. Comprehensive information on optics makes this book the definitive source on the subject. A bright, two-color design enhances the text and aids the reader's understanding. Completely updated and revised to present the latest information in the field. All illustrations are now highlighted with a second color to aid understanding. A new color plate section provides clear, excellent-quality photographs to vividly illustrate important concepts. More information is included on aspheric lenses, with a new chapter on aspheric lenses. Many new questions and exercises reinforce important points and help readers understand the material. The contents have been entirely reorganized for a more logical, easy-to-follow approach. A new glossary defines all key terms from the chapters for convenient reference.

Now thoroughly revised to reflect state-of-the-art advances in the field, Botulinum Toxin in Facial Rejuvenation, 2nd Edition, covers the entire range of the use of botulinum toxin for cosmetic purposes. Dr. Kate Coleman offers practical guidance for safe handling, selection and assessment of patients, potential complications and pitfalls, and aesthetic techniques, as well as comparative modalities and long-term management. This is an ideal resource for anyone who offers this sought-after procedure, including cosmetic surgeons, oculoplastic surgeons, dermatologists, physician's assistants, and registered nurses. Features new, unique coverage of long-term management, picturing the same original patients 15 years later, as well as observations on how treatments should be adjusted as the patient gets older in order to respond to natural changes in bone density and underlying support structures. Presents new knowledge on neuromodulation and how treatment can be used to 'retrain' expressions to provide fewer frowns lines and better facial symmetry. Offers comparative information on other modalities such as laser and hyaluronic acid, as well as potential risk factors, so you can choose the best procedure for each patient. Discusses the various forms of botulinum toxin currently available on the market, with an emphasis on Botox, Xeomin, and Dysport. Uses full-color clinical photos of pre-, peri-, and post-operative results to illustrate nuances of techniques as well as the effectiveness of botulinum toxin on wrinkles and scars for the major facial areas. Provides current guidelines on treatment methods and best practices for reconstitution and storage. Discusses which patients may be at risk for adverse effects?or "worsening results"?and offers suitable alternatives. Enhanced eBook version included with purchase. Your enhanced eBook allows you to access all of the text, figures, and references from the book on a variety of devices.

Die Hornhauttransplantation hat sich seit der ersten erfolgreichen Keratoplastik im Jahre 1905 zu einem Routineeingriff entwickelt, trotzdem ist die Bereitstellung von Spendermaterial in Deutschland noch unzureichend. Zur Losung dieses wesentlichen Problems soll die Etablierung von Hornhautbanken beitragen. Das vorliegende Buch gibt hierfur eine Anleitung. Gleichzeitig ist es als Nachschlagewerk fur bereits auf dem Gebiet des "Eyebankings" Erfahrene gedacht. Im ersten deutschsprachigen Werk zu diesem Thema ist es den Herausgebern gelungen, fur die Beantwortung der verschiedenen Fragestellungen- von gesetzlichen Grundlagen der Hornhauttransplantation uber technische Ablaufe bei der Gewinnung und Konservierung von Transplantaten bis hin zur Finanzierung von Hornhautbanken- kompetente Autoren aus der "Arbeitsgemeinschaft Deutscher Hornhautbanken" zu gewinnen."

Neueste Erkenntnisse aus Biomechanik und Klinik ermoeglichen eine computerunterstutzte Darstellung der Augenmotilitat von Schielen und komplexen Augenmotilitatsstoerungen. Die biomechanischen Faktoren und die grundsatzlichen Operationsmethoden werden aufgezeigt. Die funktionelle Anatomie des Augenbewegungsapparates und dessen zentraler Steuerung, die anschauliche Beschreibung einfacher mathematischer Grundlagen der Okulomotorik und biomechanischer Augenmodelle, die Darstellung einer "funktionellen Topographie" als Orientierungshilfe fur die Diagnostik und Simulation stehen im Mittelpunkt. An Beispielen werden parallel klinische und biomechanische Gesichtspunkte der Messung, Differentialdiagnostik und Simulation horizontaler und vertikaler Motilitatsstoerungen besprochen. Ein interaktives Computerprogramm (SEE++) zur Simulation von Motilitatsstoerungen sowie deren operativer Korrektur liegt als CD bei. Ein umfangreiches Literaturverzeichnis sowie zahlreiche Abbildungen und Tabellen vervollstandigen das Buch.

Chandler and Grant's Glaucoma - one of the field's seminal texts on the medical practice and surgical management of glaucoma, now in its Sixth Edition - includes the latest updates in an area that is currently experiencing a surge of innovation. Edited by Drs. Malik Y. Kahook and Joel S. Schuman and with contributions from the late David L. Epstein and more than 80 contributors, Chandler and Grant's Glaucoma, Sixth Edition brings together the experience of world-class glaucoma experts who belong to a long line of surgeons trained using the teachings of the original authors of this classic work. Each chapter has been meticulously edited and updated from the previous edition, while maintaining the well-established historical teachings of Drs. Paul A. Chandler and W. Morton Grant. New chapters on medical therapy as well as thorough updates on novel and minimally invasive approaches for the surgical management of glaucoma have been added. New topics and features in the Sixth Edition include: Advances in imaging of the optic nerve and retina Rho-associated protein kinase (ROCK) inhibitors Glaucoma and cerebrospinal fluid pressure The US Food and Drug Administration's role in the development of new diagnostic and surgical devices for patients with glaucoma Chandler and Grant's Glaucoma has been the most relevant and invaluable reference on glaucoma for generations of ophthalmologists. This updated Sixth Edition builds on the teachings of previous editions, making the Sixth Edition as relevant in the 21st century as when the first lectures were presented by Drs. Chandler and Grant more than 55 years ago.

Management of Vitreo-Retinal Disease: A Surgical Approach provides a comprehensive guide to the diagnosis, clinical management and surgery of many retinal disorders. As such it will be invaluable to both trainee and consultant ophthalmologists but will also be very useful to optometrists and ophthalmic opticians who are becoming increasingly involved in the diagnosis and treatment of ophthalmic disorders. The authors' wealth of experience in the field is presented to the reader in a didactic text supported by illustrations and photographs (many in colour) which enable the reader to readily convert the knowledge presented into practice.

If you have been diagnosed with cataracts or are concerned you may have them, get detailed and understandable answers to your questions with Cataracts: A Patient's Guide to Treatment, Third Edition, newly updated to include the latest information on rapidly-evolving cataract surgical and lens implant technologies. Even though cataract surgery is performed several million times a year, it is common for patients to have questions, concerns, and misconceptions when it comes to the surgery. This useful resource covers the most commonly-asked questions with clear, understandable explanations. Two foremost cataract experts walk readers through the procedure and explain why cataracts form, how they are diagnosed, how they are treated, and what other eye conditions may affect cataract surgery, all in a way that is easily understandable for patients and their families. Easy-to-read and brief in length, it nonetheless provides comprehensive information on patient-specific issues that affect cataract surgery success and outcomes. It serves as an excellent supplement to information and advice obtained from the patient's own eye doctor. A few of the questions answered inside Cataracts: A Patient's Guide, Third Edition are: How are cataracts diagnosed? How do I know if I should have cataract surgery? What kind of anaesthesia is used during surgery? Which of the intraocular lens implant options should I consider? What is the role of lasers in cataract surgery? What is the recovery like after surgery? Will I still need glasses or contacts after surgery? Can I have surgery if I have glaucoma or other eye conditions? After reading this book, you will be able to make a well-informed decision about cataract surgery and will understand much more about the range of artificial lens implant options that can get you seeing clearly again.

This second edition is the result of a collaborative effort of ophthalmic pathologists from 11 countries and is more extensive and detailed than its predecessor published in 1980. Several new tumour entities have been added, while the list of histological variants has been expanded and examples of immunoreactivity included. The publication of the revised eye and adnexal tumour classification is accompanied by 112 photomicrographs.

This second edition of Low Vision Rehabilitation: A Practical Guide for Occupational Therapists provides current, evidence-based information on low vision rehabilitation that contains several new and expanded chapters on ADLs, IADLs, and recreation, as well as new online resources and the latest in accessibility devices. Low vision rehabilitation is rapidly growing as a specialty practice for occupational therapists. This growth requires practical, evidence-based information on the evaluation and treatment of the effects of low vision on occupational performance. Responding to this need, Low Vision Rehabilitation: A Practical Guide for Occupational Therapists, Second Edition blends standards of practice that have been developed for over 50 years by low vision therapists and optometrists, with the latest scientific research and the unique perspective of occupational therapists. This text presents a new standard of low vision rehabilitation in which occupational therapists practice as part of a team of vision rehabilitation professionals serving patients with low vision. Authors Stephen Whittaker, a low vision researcher, certified low vision therapist and occupational therapist, Mitchell Scheiman, an optometrist and researcher, and Debra Sokol-McKay, an occupational therapist with specialty certification in low vision as well as certification as a low vision therapist, vision rehabilitation therapist and diabetes educator, have carefully selected evidence-based evaluations and treatments that focus on clinical practicality and meaningful occupational goals in all patients from children to older adults. New to the Second Edition: A focus on occupational performance using "whatever works," whether visual, non-visual, or a combination of these different devices and adaptive techniques The "EPIC" Framework, a general strategy to organize a treatment plan for daily activities using visual and non-visual techniques Access to a companion website designed as a handy clinical reference, with solutions to clinical problems easily searchable and cross-linked to related content The "Success-Oriented Approach" to interventions based on the most recent research on cognitive disability and depression associated with low vision Applications of the latest electronic accessibility devices including smartphones, tablets, and magnifiers that read aloud Incorporates the AADE (TM) 7 Self-Care Behavior framework of the American Association of Diabetes Educators Incorporates concepts from the latest edition of the AOTA Occupational Therapy Practice Framework: Domain and Process Instructors in educational settings can visit www.efacultylounge.com for additional materials to be used for teaching in the classroom. Features Included: Recommended practical evaluation and treatment methods such as a 1 hour evaluation protocol, how to write observable and measurable goals and document outcomes, and specific instructions on how to implement treatments Prepares therapists for the ACVREP certification as a low vision therapist or vision rehabilitation or AOTA specialty certification in low vision Emphasizes intervention and low vision rehabilitation treatment including: modification of the environment adaptive visual and non-visual techniques selection and use of non-optical assistive devices selection and use of electronic and optical devices and use of computer technology including smartphones and tablets Comprehensive case studies on vision impairment resulting from eye disease to head injury and more Provides valuable information on how to start an independent practice in low vision rehabilitation Includes a chapter on diabetes management Low Vision Rehabilitation: A Practical Guide for Occupational Therapists, Second Edition employs an interdisciplinary perspective that is unique, practical, and credible and will benefit Occupational Therapy and Occupational Therapy Assistant students, as well as practicing clinicians interested in specializing in low vision or other health care practitioners for patients with vision impairment.

This is a self-assessment book for candidates for postgraduate examina tions in ophthalmology. It covers all of the sciences fundamental to o phthalmology: anatomy (60 multiple choice questions), physiology (93 m ultiple choice questions), pharmacology (36), pathology (33), and micr obiology (42). Questions are grouped according to specialty area, foll owed by True/False Answers that are all supported with concise explana tions. The book can therefore be used for learning as well as practice . The book's most innovative feature is the set of 21 constructed essa y plans, covering the major topics of concern in this field. It is not oriously difficult to provide model answers to essay questions, but he re the authors have developed a new, highly visual approach with the c onsistent use of icons, to provide an at-a-glance understanding.

The management of emergent neuro-ophthalmic conditions can be a life-saving encounter for the general ophthalmologist. This book covers life-threatening scenarios that a general ophthalmologist might encounter, and is designed to help the ophthalmologist make emergency triage decisions for initial evaluation and treatment of potentially vision- or life-threatening conditions. This book is case based, and provides the reader with the invaluable expert views of two neuro-ophthalmologists. One, Dr Lee is an ophthalmology-based neuro-ophthalmologist and the other, Dr Brazis is a neurology-based neuro-ophthalmologist. Dr Mughal and Dr Policeni collected and collated the case vignettes during their fellowship with Dr Lee at the University of Iowa Hospitals and Clinics. This textbook provides a concise, easy to read, and practical guide to the emergent evaluation of neuro-ophthalmic conditions. It is designed to be a quick read and not to be all-inclusive or comprehensive. The reader is directed to longer and more comprehensive neuro-ophthalmic texts for this information. It is also not the aim of the book to provide information on anatomy, pharmacology, physiology, or other basic mechanisms of disease. Instead, this text is meant to be a quick reference and resource for the clinician in the emergency room or in the clinic facing a potentially vision- or life-threatening emergency and to provide immediate guidance for potentially "high stakes" decision making. The case vignettes are based upon real clinical cases but the clinical details of each case have been modified for teaching purposes and represent composite rather than individual histories.

Are you a medical student, resident, or fellow trying to absorb as much information on the basics of retina surgery as efficiently as possible? Are you a general ophthalmologist who needs a quick refresher on a complex procedure? Reach into your lab coat pocket and pull out The Pocket Guide to Vitreoretinal Surgery, for easy access to the essential information you need right now. Dr. Jason Crosson and colleagues have designed this book as the ultimate quick-read manual on retina surgery, using a conversational tone that allows readers to retain information in the most effective manner. Medical students, residents, and fellows will be delighted to use this accessible, high-yield handbook during their rotations to familiarize themselves with the "nuts and bolts" of retina surgery, while general ophthalmologists will be glad to have it as a quick reference guide to current best practices. Each chapter in The Pocket Guide to Vitreoretinal Surgery is arranged in short, easy to read sections, and is accompanied by numerous color photographs to aid in recognition and retention.