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Numerical modelling of the human eye accommodation
KTH, School of Engineering Sciences (SCI), Mechanics, Structural Mechanics.
2005 (English)Licentiate thesis, comprehensive summary (Other scientific)
Abstract [en]

This thesis addresses the biomechanics of the human eye accommodation. It deals with the development of numerical model of a 29-year-old eye, incorporating the vitreous body as a part of accommodative apparatus. A more complete understanding of the mechanism of accommodation becomes increasingly important as new types of lens implants and surgical procedures to correct both accommodative loss in aphakia as well as in the aging process are being explored. It is necessary to conduct the experimental and analytical studies to gain a better comprehension on ophthalmologic processes. The accommodation has been investigated through numerical simulations based on finite element analysis. The extensive literature survey was the platform for establishing relevant modelling procedures. The calculations were carried out using the commercial general-purpose finite element software ABAQUS. All materials were modelled as being linearly elastic and the interiors on the lens and vitreous were assumed to be incompressible. Present research seeks to investigate the validity of some fundamental assumptions about the construction and functioning of human accommodation system. The model is rather general and involves the synthesis of disparate sets of geometric and mechanical data from a variety of published sources. Different configurations of the structural model can easily be simulated by appropriate adjustments of parameters. The results of this study are broadly in agreement with published observations. The model behaviour is consistent with classical Helmholtz theory. It is shown that such a modelling exercise captures at least some physiological aspects of human accommodation. The proposed procedures and developed inverse methodology can be a useful tool to derive previously not documented parameters and test the consistency of different sets of experimental measurements. The obtained results can be used to draw some recommendations in pursuit of the clinical imperatives of ophthalmologists.

Place, publisher, year, edition, pages
Stockholm: KTH , 2005. , p. x, 56
Series
Trita-MEK, ISSN 0348-467X ; 2005:14
National Category
Other Industrial Biotechnology
Identifiers
URN: urn:nbn:se:kth:diva-4078OAI: oai:DiVA.org:kth-4078DiVA, id: diva2:10648
Supervisors
Note
QC 20101213Available from: 2006-08-17 Created: 2006-08-17 Last updated: 2010-12-13Bibliographically approved
List of papers
1. Numerical study of the effect of vitreous support on eye accommodation
Open this publication in new window or tab >>Numerical study of the effect of vitreous support on eye accommodation
2005 (English)In: Acta of Bioengineering and Biomechanics, ISSN 1509-409X, Vol. 7, no 2, p. 3-15Article in journal (Refereed) Published
Abstract [en]

The aim of the current work was to extend previously created finite element models of accommodation such as the one by BURD [2] by addition of vitreous. The zonule consisted of anterior and central sets and vitreous was modelled as a linear clastic incompressible body. An inverse method was used to find some important, previously not documented, aspects. The model was found to behave according to the expectations, with results consistent with classical Helmholtz theory.

Keyword
Eye accomodation, Finite element models, Vitreous support, accommodation, adult, article, finite element analysis, human, human experiment, lens, optical resolution, quantitative study, vitreous body
National Category
Other Industrial Biotechnology
Identifiers
urn:nbn:se:kth:diva-27324 (URN)2-s2.0-33846348272 (Scopus ID)
Note

QC 20101209

Available from: 2010-12-09 Created: 2010-12-09 Last updated: 2014-04-07Bibliographically approved
2. Aspects of eye accommodation evaluated by finite elements
Open this publication in new window or tab >>Aspects of eye accommodation evaluated by finite elements
2008 (English)In: Biomechanics and Modeling in Mechanobiology, ISSN 1617-7959, E-ISSN 1617-7940, Vol. 7, no 2, p. 139-150Article in journal (Refereed) Published
Abstract [en]

Axisymmetric nonlinear finite models of accommodation incorporating the posteriorly sloped force and vitreous effects have been studied by means of their effectiveness in mechanical and optical performances. All materials were assumed to be linearly elastic, vitreous and lens matrices were incompressible. The present model is subjected to certain indicated shortcomings, however, the behavior of the model is predictable, reasonable and favourably consistent with different published data, supporting the Helmholtz theory of accommodation.

Keyword
human crystalline lens, scleral expansion surgery, human ciliary, muscle, suspensory apparatus, elastic constants, zonular apparatus, refractive-index, presbyopia, age, mechanism
Identifiers
urn:nbn:se:kth:diva-17442 (URN)10.1007/s10237-007-0081-2 (DOI)000254785100005 ()2-s2.0-41149181302 (Scopus ID)
Note
QC 20100525Available from: 2010-08-05 Created: 2010-08-05 Last updated: 2017-12-12Bibliographically approved

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