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J. R. Kuszak, M. Mazurkiewicz, E. A. Knighton, J. Brandt, S. Vogt, A. J. O'Brien, R. Zoltoski; Computer Modeling the Anatomical Relationship of Accommodation and Compaction in the Human Lens. Invest. Ophthalmol. Vis. Sci. 2009;50(13):2799.
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© ARVO (1962-2015); The Authors (2016-present)
To correlate quantitative developmental, growth and age-related changes in human lenses at the fiber level (width, thickness, shape, organization and surface morphology) in order to create a dynamic computer model that recreates the anatomical relationship of accommodation and compaction in the human lens.
We employ a metanalytic approach gathering quantitative data on fiber structure from the literature as well as from current and archival results of numerous anatomical studies of crystalline lenses conducted in our laboratory in the last three decades. This data is used to create detailed and accurate scale 2 and 3D computer-assisted drawings (CADs) of lenses at different ages and in varied states of function and stages of disease. In addition, since correctly fixed and/or chemically preserved biological tissue represents a literally instantaneous cessation of life processes at a defined point in time, we restore the dynamism of lens function by placing the scale and temporally or functionally defined CADs on a timeline and then create an animated sequence of that life process.
At birth, the lens (~4 mm thick x 6 mm wide) consists of ~1900 growth shells (GSs) comprised of fibers (organized as Y sutures) with blunt ends that preclude accommodation (birth = 0 D). By the end of infancy the lens (~ 3.6 mm thick x 8.0 mm wide) has grown by adding ~665 GSs comprised of fibers (progressively organized into 6 branch star sutures) with flared and flattened ends that enable accommodation. (2 - 4 yrs old = 8-20D) Throughout childhood and adolescence the lens (~3.4 mm thick x 8.8 mm wide) grows by the adding ~335 GSs (progressively organized into 9 branch star sutures) with more flared and flatter ends that further facilitate dynamic focusing (4 - 18 yrs old = 10-20D). At the end of life (75+ yrs old) the lens (5.3 mm thick x 9.4 mm wide) consisted of ~3100 GSs comprised of fibers (progressively organized into 12 branch complex star sutures) with the most flared and flattest ends. However, the lens has no dioptric power at that time.
There is a direct relationship between fiber anatomy, accommodation and compaction. During accommodation, as the flattened fiber ends of hundreds of concentric GSs become more intercalated at sutures, thereby increasing surface curvature, the concomitant decrease in their diameter, forces the crumpling or compaction of nuclear fibers that have blunt ends.
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