[PDF] The Mathematical Modelling Of Flow And Deformation In The Human Eye eBook

Author : R. Collins
Publisher : Springer Science & Business Media
Page : 111 pages
File Size : 32,53 MB
Release : 2013-03-08
Category : Mathematics
ISBN : 3642501532

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A rich and abundant literature has developed during the last half century dealing with mechanical aspects of the eye, mainly from clinical and, experimental points of view. For the most part, workers have attempted to shed light on the complex set of conditions known by the general term glaucoma. These conditions are characterised by an increase in intraocular pressure sufficient to cause de generation of the optic disc and concomitant defects in the visual field, which, if not controlled, lead to inevitable permanent blindness. In the United States alone, an estimated 50,000 persons are blind as a result of glaucoma, which strikes about 2% of the population over 40 years of age (Vaughan and Asbury, 1974). An understanding of the underlying mechanisms of glaucoma is hindered by the fact that elevated intraocular pressure, like a runny nose, is but a symptom which may have a variety of causes. Only by turning to the initial pathology can one hope to understand this important class of medical problems.

Author : E. Y. K. Ng
Publisher : CRC Press
Page : 432 pages
File Size : 39,50 MB
Release : 2012-06-05
Category : Technology & Engineering
ISBN : 1439869936

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Advanced image processing and mathematical modeling techniques are increasingly being used for the early diagnosis of eye diseases. A comprehensive review of the field, Human Eye Imaging and Modeling details the latest advances and analytical techniques in ocular imaging and modeling. The first part of the book looks at imaging of the fundus as well as infrared imaging. It begins by exploring developments in the analysis of fundus images, particularly for the diagnosis of diabetic retinopathy and glaucoma. It also reviews anterior segment imaging and reports on developments in ocular thermography, especially the use of thermal imaging as the basis of tear evaporimetry and dry eye diagnosis. The second part of the book delves into mathematical modeling of the human eye. Coverage includes modeling of the eye during retinal laser surgery, a framework for optical simulation, heat distribution using a 3D web-splines solution, and exposure to laser radiation. The text also examines computer simulation of the human eye based on principles of heat transfer, as well as various bioheat equations to predict interior temperatures based on the surface temperature. Featuring contributions by established experts in eye imaging, this is a valuable reference for medical personnel and researchers who want to know more about state-of-the-art computer-based imaging and detection methods. It presents novel imaging and modeling algorithms that can aid in early diagnosis, with the aim of enriching the lives of people suffering from eye abnormalities.

Author : Nikos Paragios
Publisher : Springer Science & Business Media
Page : 612 pages
File Size : 31,57 MB
Release : 2006-01-16
Category : Computers
ISBN : 0387288317

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Abstract Biological vision is a rather fascinating domain of research. Scientists of various origins like biology, medicine, neurophysiology, engineering, math ematics, etc. aim to understand the processes leading to visual perception process and at reproducing such systems. Understanding the environment is most of the time done through visual perception which appears to be one of the most fundamental sensory abilities in humans and therefore a significant amount of research effort has been dedicated towards modelling and repro ducing human visual abilities. Mathematical methods play a central role in this endeavour. Introduction David Marr's theory v^as a pioneering step tov^ards understanding visual percep tion. In his view human vision was based on a complete surface reconstruction of the environment that was then used to address visual subtasks. This approach was proven to be insufficient by neuro-biologists and complementary ideas from statistical pattern recognition and artificial intelligence were introduced to bet ter address the visual perception problem. In this framework visual perception is represented by a set of actions and rules connecting these actions. The emerg ing concept of active vision consists of a selective visual perception paradigm that is basically equivalent to recovering from the environment the minimal piece information required to address a particular task of interest.

Author : Pier Giorgio Gobbi
Publisher : SPIE-International Society for Optical Engineering
Page : 0 pages
File Size : 31,23 MB
Release : 2013
Category : Eye
ISBN : 9780819492548

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This book provides a faithful and robust simulation of the optical and visual performances of the human eye for axial vision of distant objects in a variety of visual conditions. The author moves from intrinsically theoretical aspects (the optical and neurophysical models of the eye) to include a great number of experimental measurements from the scientific literature, in order to adapt the model parameters to the observed phenomenology and validate the predictivity power of the models themselves. The results are very satisfactory in terms of quantitative and qualitative adherence of model predictions to field measurements. Resulting from the author's investigations over the last decade, the book material is largely original, and the most relevant achievement can be found in the capacity to evaluate visual acuity for a range of visual conditions, such as variations in pupil size, refractive error, and ambient illumination. Thanks to the general organisation of the book, chapters and paragraphs with high level mathematical and physical optics content can be safely skipped without compromising the overall comprehension.To this end, a brief summary is provided at the end of each chapter, making this book appropriate for readers with greatly varying degrees of technical knowledge.

Author : P. Causin
Publisher : Kugler Publications
Page : 198 pages
File Size : 12,12 MB
Release : 2014-12-17
Category : Medical
ISBN : 9062992412

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ForewordThe human eye offers the extraordinary possibility to visualize and monitor non-invasively, in vivo, in humans, many morphological and haemodynamical features. Therefore, a large amount of data on ocular structures and macro- and micro-circulation can be obtained in a clinical setting during a patient's visit. However, the interpretation of these data remains a very challenging task, since the understanding of the physiology, bio-mechanics and fluid-dynamics of the human eye remains scarce. This unmet gap between the availability of imaging data and their elusive clinical interpretatio...

Author : Giovanna Guidoboni
Publisher : Springer Nature
Page : 606 pages
File Size : 49,80 MB
Release : 2019-11-25
Category : Mathematics
ISBN : 3030258866

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The chapters in this contributed volume showcase current theoretical approaches in the modeling of ocular fluid dynamics in health and disease. By including chapters written by experts from a variety of fields, this volume will help foster a genuinely collaborative spirit between clinical and research scientists. It vividly illustrates the advantages of clinical and experimental methods, data-driven modeling, and physically-based modeling, while also detailing the limitations of each approach. Blood, aqueous humor, vitreous humor, tear film, and cerebrospinal fluid each have a section dedicated to their anatomy and physiology, pathological conditions, imaging techniques, and mathematical modeling. Because each fluid receives a thorough analysis from experts in their respective fields, this volume stands out among the existing ophthalmology literature. Ocular Fluid Dynamics is ideal for current and future graduate students in applied mathematics and ophthalmology who wish to explore the field by investigating open questions, experimental technologies, and mathematical models. It will also be a valuable resource for researchers in mathematics, engineering, physics, computer science, chemistry, ophthalmology, and more.

Author : Matteo Carlo Maria Aletti
Publisher :
Page : 0 pages
File Size : 49,34 MB
Release : 2017
Category :
ISBN :

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The structure of the eye offers a unique opportunity to directly observe the microcirculation, by means, for instance, of fundus camera, which are cheap devices commonly used in the clinical practice. This can facilitate the screening of systemic deseases such as diabetes and hypertension, or eye diseases such as glaucoma. A key phenomenon in the microcirculation is the autoregulation, which is the ability of certain vessels to adapt their diameter to regulate the blood flow rate in response to changes in the systemic pressure or metabolic needs. Impairments in autoregulation are strongly correlated with pathological states. The hemodynamics in the eye is influenced by the intraocular pressure (IOP), the pressure inside the eye globe, which is in turn influenced by the ocular blood flow. The interest in the IOP stems from the fact that it plays a role in several eye-diseases, such as glaucoma. Mathematical modelling can help in interpreting the interplay between these phenomena and better exploit the available data. In the first part of the thesis we present a simplified fluid-structure interaction model that includes autoregulation. A layer of fibers in the vessel wall models the smooth muscle cells that regulate the diameter of the vessel. The model is applied to a 3D image-based network of retinal arterioles. In the second part, we propose a multi-compartments model of the eye. We use the equations of poroelasticity to model the blood flow in the choroid. The model includes other compartments that transmit the pulsatility from the choroid to the anterior chamber, where the measurements of the IOP are actually performed. We present some preliminary results on the choroid, the aqueous humor and on the choroid coupled with the vitreous. Finally, we present a reduced order modelling technique to speed up multiphysics simulations. We use high fidelity models for the compartments of particular interest from the modelling point of view. The other compartments are instead replaced by a reduced representation of the corresponding Steklov-Poincaré operator.

Author : Rajendra Acharya U
Publisher : Artech House
Page : 378 pages
File Size : 15,53 MB
Release : 2008
Category : Computers
ISBN : 1596932090

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This groundbreaking resource gives you full details on state-of-the-art 2D and 3D eye imaging and modeling techniques that are paving the way to breakthrough clinical applications in eye health. ItOCOs the first book to explore in depth a new generation of computational methods that combine image processing, simulation, and statistical discrimination tools in efforts to improve early detection of cataracts, diabetic retinopathy, glaucoma, iridocyclitis, corneal haze, maculopathy, and other visual impairments and conditions."

Author : John Enderle
Publisher : Springer Nature
Page : 151 pages
File Size : 46,68 MB
Release : 2022-06-01
Category : Technology & Engineering
ISBN : 3031016424

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There are five different types of eye movements: saccades, smooth pursuit, vestibular ocular eye movements, optokinetic eye movements, and vergence eye movements. The purpose of this book is focused primarily on mathematical models of the horizontal saccadic eye movement system and the smooth pursuit system, rather than on how visual information is processed. A saccade is a fast eye movement used to acquire a target by placing the image of the target on the fovea. Smooth pursuit is a slow eye movement used to track a target as it moves by keeping the target on the fovea. The vestibular ocular movement is used to keep the eyes on a target during brief head movements. The optokinetic eye movement is a combination of saccadic and slow eye movements that keeps a full-field image stable on the retina during sustained head rotation. Each of these movements is a conjugate eye movement, that is, movements of both eyes together driven by a common neural source. A vergence movement is a non-conjugate eye movement allowing the eyes to track targets as they come closer or farther away. In this book, early models of saccades and smooth pursuit are presented. The smooth pursuit system allows tracking of a slow moving target to maintain its position on the fovea. Models of the smooth pursuit have been developed using systems control theory, all involving a negative feedback control system that includes a time delay, controller and plant in the forward loop, with unity feedback. The oculomotor plant and saccade generator are the basic elements of the saccadic system. The oculomotor plant consists of three muscle pairs and the eyeball. A number of oculomotor plant models are described here beginning with the Westheimer model published in 1954, and up through our 1995 model involving a 4$^{th}$ order oculomotor plant model. The work presented here is not an exhaustive coverage of the field, but focused on the interests of the author. In Part II, a state-of-art model of the saccade system is presented, including a neural network that controls the system. Table of Contents: Introduction / Smooth Pursuit Models / Early Models of the Horizontal Saccadic Eye Movement System / Velocity and Acceleration Estimation / 1995 Linear Homeomorphic Saccadic Eye Movement Model