Nonlinear Finite Element Model Analysis of Human Accommodation Lens PDF Download
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Author: Tri Le
Publisher:
ISBN: 9780542226847
Category : Engineering, Civil
Languages : en
Pages :
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Book Description
The crystalline human lens is modeled by using the finite element software, ABAQUS/CAE Version 6.5-1 as an axisymmetric shell to study the optical power and displacement of anterior and posterior poles induced due to zonule traction. Several different element types were tested to obtain the optimum mesh. These elements were three and six-noded triangular hybrid and four-noded quadrilateral hybrid for modeling of the cortex and nucleus. Constant strain triangular and regular quadrilateral elements were examined for modeling the capsule. One dimensional two degree of freedom spring elements were used to model the anterior, posterior, and equatorial zonules. Six different lens profiles were selected to mathematically model the lens geometry, which included Lizak; Krueger A; Krueger B; Strenk A; Strenk B; and Trial lens. A displacement-based incremental loading history was applied to the equatorial zonule to conduct geometric nonlinear analysis. The converged solution was obtained by coupling Hilbert L-2 norm and equating external work done to internal system strain energy. The converged and optimum solution was compared with analytical solution reported in literature and was selected to conduct a comprehensive parametric study. (Abstract shortened by UMI.).
Author: Tri Le
Publisher:
ISBN: 9780542226847
Category : Engineering, Civil
Languages : en
Pages :
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Book Description
The crystalline human lens is modeled by using the finite element software, ABAQUS/CAE Version 6.5-1 as an axisymmetric shell to study the optical power and displacement of anterior and posterior poles induced due to zonule traction. Several different element types were tested to obtain the optimum mesh. These elements were three and six-noded triangular hybrid and four-noded quadrilateral hybrid for modeling of the cortex and nucleus. Constant strain triangular and regular quadrilateral elements were examined for modeling the capsule. One dimensional two degree of freedom spring elements were used to model the anterior, posterior, and equatorial zonules. Six different lens profiles were selected to mathematically model the lens geometry, which included Lizak; Krueger A; Krueger B; Strenk A; Strenk B; and Trial lens. A displacement-based incremental loading history was applied to the equatorial zonule to conduct geometric nonlinear analysis. The converged solution was obtained by coupling Hilbert L-2 norm and equating external work done to internal system strain energy. The converged and optimum solution was compared with analytical solution reported in literature and was selected to conduct a comprehensive parametric study. (Abstract shortened by UMI.).
Author: Ronald A. Schachar
Publisher: Kugler Publications
ISBN: 9062992331
Category : Anatomy
Languages : en
Pages : 280
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Book Description
The human eye is a remarkable optical device. In less than a second, a young human eye can accommodate from infinity to closer than 10 cm. Accommodation occurs with minimal effort and can be rapidly repeated with no apparent evidence of fatigue. Unfortunately, maximum accommodation decreases throughout life and by the fifth decade leads to presbyopia, the inability to read at a normal working distance. Interestingly, the mechanism by which the human eye is able to adjust focus has been debated for over 300 years. No previous theory has been put forth that can account for all the physical chang.
Author: Benjamin Coldrick
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
Author: T. K. Hight
Publisher:
ISBN:
Category :
Languages : en
Pages : 9
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Book Description
Author: Ahmed Bahgat Fattouh Abdel-Fattah
Publisher:
ISBN:
Category : Eye
Languages : en
Pages : 326
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Book Description
Author: Matthew A. Reilly
Publisher: Frontiers Media SA
ISBN: 2832550398
Category : Technology & Engineering
Languages : en
Pages : 187
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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.
Author: Kazuo Tsubota
Publisher: Taylor & Francis US
ISBN: 0824755235
Category : Medical
Languages : en
Pages : 320
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Book Description
Examining established and emerging treatments for the correction of hyperopia and presbyopia, this reference offers guidance on technologies such as thermal or conductive keratoplasty, corneal implants, laser scleral relaxation, scleral expansion rings, intraocular lenses, and LASIK modifications.
Author: Thomas H Williamson
Publisher: Springer
ISBN: 3319279904
Category : Medical
Languages : en
Pages : 176
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Book Description
This book instructs postgraduate trainees in ophthalmology on the basic methodology required to perform intraocular surgery. The text is written clearly and concisely, investigating basic surgical skills for the eye to facilitate the training process. The subject material of each chapter has been carefully chosen to explain separate conceptual areas in surgery to allow easy understanding and rapid attainment of knowledge. The concepts can be transferred from one surgical method to another, giving the reader the flexibility to adapt to new methods quickly. Intraocular Surgery - A Basic Surgical Guide provides various insights to allow the development of a thoughtful and considered approach to surgery. It encourages the reader to more intelligently scrutinize which surgical methods to apply, and to utilize the most effective procedures in clinical practice. After reading this book, the reader will be well-equipped to perform the simple steps of surgery, improving the overall quality of surgery.
Author: Begoña Calvo Lopez
Publisher: Springer Science & Business Media
ISBN: 9400745524
Category : Technology & Engineering
Languages : en
Pages : 196
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Book Description
This book addresses patient-specific modeling. It integrates computational modeling, experimental procedures, imagine clinical segmentation and mesh generation with the finite element method (FEM) to solve problems in computational biomedicine and bioengineering. Specific areas of interest include cardiovascular problems, ocular and muscular systems and soft tissue modeling. Patient-specific modeling has been the subject of serious research over the last seven years and interest in the area is continually growing and this area is expected to further develop in the near future.
Author:
Publisher:
ISBN:
Category : Bioengineering
Languages : en
Pages : 978
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Book Description
