Modeling internal stress distributions in the human lens: Can opponent theories coexist?

A. Belaidi, B. K. Pierscionek

    Research output: Contribution to journalArticle

    22 Citations (Scopus)

    Abstract

    The effects of material properties and equatorial stretching forces on the stress distribution and shape pro. le of human lenses were investigated to see whether support could be found for either or both current theories of accommodation. Finite element analysis was used to create models using shape parameters and material properties from published data. Models were constructed for two lenses of different ages. Material properties were varied to show differences between models with a single elastic modulus and those with different moduli for the cortex and the nucleus. Two levels of stretching forces were applied at the equator. Comparisons between experimental and model profiles were made, and stress distribution patterns were constructed. In all models, stretching produces a flattening in the peripheral curvature of the lens. In the younger lens, model and experimental results show that central curvature at some points is steeper for stretched than for unstretched profiles. In the older lens, gradients are flatter at all central points for stretched model and experimental profiles compared to the unstretched profile. In all models, there is a region of higher stress distribution within the lens that corresponds with the position of an infection point that appears on the anterior surface and, in the older lens, also on the posterior surface. The results show that equatorial stretching forces can produce shape changes in support of both current theories of accommodation depending on the lens age, shape, and applied force.
    LanguageEnglish
    Pages1
    JournalJournal of Vision
    Volume7
    Issue number11
    DOIs
    Publication statusPublished - 2007

    Fingerprint

    stress distribution
    residual stress
    lenses
    accommodation
    profiles
    curvature
    cortexes
    flattening
    infectious diseases
    equators
    modulus of elasticity
    gradients
    nuclei

    Cite this

    Belaidi, A. ; Pierscionek, B. K. / Modeling internal stress distributions in the human lens: Can opponent theories coexist?. In: Journal of Vision. 2007 ; Vol. 7, No. 11. pp. 1.
    @article{e61002b34f924b1a90ba6da31ec1c020,
    title = "Modeling internal stress distributions in the human lens: Can opponent theories coexist?",
    abstract = "The effects of material properties and equatorial stretching forces on the stress distribution and shape pro. le of human lenses were investigated to see whether support could be found for either or both current theories of accommodation. Finite element analysis was used to create models using shape parameters and material properties from published data. Models were constructed for two lenses of different ages. Material properties were varied to show differences between models with a single elastic modulus and those with different moduli for the cortex and the nucleus. Two levels of stretching forces were applied at the equator. Comparisons between experimental and model profiles were made, and stress distribution patterns were constructed. In all models, stretching produces a flattening in the peripheral curvature of the lens. In the younger lens, model and experimental results show that central curvature at some points is steeper for stretched than for unstretched profiles. In the older lens, gradients are flatter at all central points for stretched model and experimental profiles compared to the unstretched profile. In all models, there is a region of higher stress distribution within the lens that corresponds with the position of an infection point that appears on the anterior surface and, in the older lens, also on the posterior surface. The results show that equatorial stretching forces can produce shape changes in support of both current theories of accommodation depending on the lens age, shape, and applied force.",
    author = "A. Belaidi and Pierscionek, {B. K.}",
    year = "2007",
    doi = "10.1167/7.11.1",
    language = "English",
    volume = "7",
    pages = "1",
    journal = "Journal of Vision",
    issn = "1534-7362",
    number = "11",

    }

    Modeling internal stress distributions in the human lens: Can opponent theories coexist? / Belaidi, A.; Pierscionek, B. K.

    In: Journal of Vision, Vol. 7, No. 11, 2007, p. 1.

    Research output: Contribution to journalArticle

    TY - JOUR

    T1 - Modeling internal stress distributions in the human lens: Can opponent theories coexist?

    AU - Belaidi, A.

    AU - Pierscionek, B. K.

    PY - 2007

    Y1 - 2007

    N2 - The effects of material properties and equatorial stretching forces on the stress distribution and shape pro. le of human lenses were investigated to see whether support could be found for either or both current theories of accommodation. Finite element analysis was used to create models using shape parameters and material properties from published data. Models were constructed for two lenses of different ages. Material properties were varied to show differences between models with a single elastic modulus and those with different moduli for the cortex and the nucleus. Two levels of stretching forces were applied at the equator. Comparisons between experimental and model profiles were made, and stress distribution patterns were constructed. In all models, stretching produces a flattening in the peripheral curvature of the lens. In the younger lens, model and experimental results show that central curvature at some points is steeper for stretched than for unstretched profiles. In the older lens, gradients are flatter at all central points for stretched model and experimental profiles compared to the unstretched profile. In all models, there is a region of higher stress distribution within the lens that corresponds with the position of an infection point that appears on the anterior surface and, in the older lens, also on the posterior surface. The results show that equatorial stretching forces can produce shape changes in support of both current theories of accommodation depending on the lens age, shape, and applied force.

    AB - The effects of material properties and equatorial stretching forces on the stress distribution and shape pro. le of human lenses were investigated to see whether support could be found for either or both current theories of accommodation. Finite element analysis was used to create models using shape parameters and material properties from published data. Models were constructed for two lenses of different ages. Material properties were varied to show differences between models with a single elastic modulus and those with different moduli for the cortex and the nucleus. Two levels of stretching forces were applied at the equator. Comparisons between experimental and model profiles were made, and stress distribution patterns were constructed. In all models, stretching produces a flattening in the peripheral curvature of the lens. In the younger lens, model and experimental results show that central curvature at some points is steeper for stretched than for unstretched profiles. In the older lens, gradients are flatter at all central points for stretched model and experimental profiles compared to the unstretched profile. In all models, there is a region of higher stress distribution within the lens that corresponds with the position of an infection point that appears on the anterior surface and, in the older lens, also on the posterior surface. The results show that equatorial stretching forces can produce shape changes in support of both current theories of accommodation depending on the lens age, shape, and applied force.

    U2 - 10.1167/7.11.1

    DO - 10.1167/7.11.1

    M3 - Article

    VL - 7

    SP - 1

    JO - Journal of Vision

    T2 - Journal of Vision

    JF - Journal of Vision

    SN - 1534-7362

    IS - 11

    ER -