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C.R. Sivertson, R.K. Zoltoski, J.R. Kuszak; Quantification of Variable Mature Fiber Length as a Function of Lens Suture Type and Age . Invest. Ophthalmol. Vis. Sci. 2003;44(13):1251.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To quantify and compare the variable "mature" fiber length within and between growth shells in lenses with "branched" (e.g., line [rabbit], Y [mouse and pig], and star [baboon and human]) sutures. Methods: The length (mm) of straight fibers (fibers that extend from either the anterior or posterior pole and delimit the proximal ends of posterior or anterior ends of suture branches, respectively) is a longitudinal portion of the circumference of an asymmetric ellipse defined by the axial dimensions of a lens.(extent determined by latitudinal degrees). Thus, their length was calculated using a standard mensuration formula incorporating lens axial dimensions ascertained under a stereo surgical dissecting microscope. The length of fibers with opposite end curvature (fibers with ends that abut and overlap to form suture branches) were taken directly from 2D SEM micrographs and then corrected for the third dimension. Results: All lenses with branched sutures exhibit a bi-sinusoidal intra-shell variation in fiber length (e.g., rabbit lens, 6.48 - 7.26mm at birth and 9.81 - 10.96mm as a young adult; mouse lens, 1.21 - 1.51mm at birth and 1.88 - 2.36mm as a young adult). The periodicity is a function of suture branch number (2 repeats for line sutures, 3 repeats for Y sutures). In these lenses, inter-shell variation in fiber length is simply a radial function. All lenses with star sutures also exhibit a bi-sinusoidal intra-shell variation in fiber length (e.g. human lens 4.86 - 6.15mm at birth and 7.48 - 9.30mm as a young adult). However, in these lenses, the periodicity increases (6 to 15) as more complex sutures are formed throughout infancy (simple star), adolescence (star), adulthood (complex star), and aging (aged star). Thus, inter-shell variation in fiber length is not simply a radial function in primate lenses. The position of both straight and opposite end curvature fibers at the equator is determined by suture type. Variation in fiber length (amplitude of the sinusoidal wave) within and between any growth shell is dependent to a minor degree on a fiber's equatorial position as a function of suture type, and to a major degree on the asymmetry of the anterior and posterior surface curvature. Conclusions: These calculations highlight the structural complexity that transforms lenses from different species into focusing elements of distinct optical quality. Animating this type of data can also be used effectively to model changes in lens structure in pathological states (cortical cataractogenesis).
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