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R.K. Zoltoski, L.R. A. Jison, M. Mazurkiewicz, J.R. Kuszak; Accommodative Range in Animal Models is Related to Lens Architecture . Invest. Ophthalmol. Vis. Sci. 2006;47(13):1982.
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© ARVO (1962-2015); The Authors (2016-present)
The purpose of this study was to quantitatively analyze the structure of commonly used animal models representative of umbilical (chicken), Y (mouse and bovine), and line (the frog and rabbit) suture lenses to show that accommodative amplitude is related to lens architecture.
Gross lens dimensions (thickness [antero–posterior axis] and width [equatorial axis]) were taken under a stereo surgical dissecting microscope. Fiber dimensions were recorded from scanning electron, light and transmission electron micrographs. Scale 3 and 4D (animations) CADs of lenses were derived from micrographs.
Chicken lenses are flattened asymmetrical oblate spheroids (ant r = 670µ, post. r = 1900µ, equatorial r = 3300µ). These dimensions are the result of meridian fibers of equal length but unequal width and thickness along length (complete taper in width at both ends, 80 and 55% taper in respectively ant. and post. thickness), becoming arranged end–to–end at the poles to form concentric growth shells. By comparison, mouse and bovine (Y suture lenses) and frog and rabbit (line suture lenses) are round asymmetrical oblate spheroids (ant. r = respectively 870, 4250, 900 and 3660µ , post. r = respectively 1080, 6900, 1370 and 4710µ, equatorial r = respectively 1250, 8500, 1900 and 5750µ). These dimensions are the result of non–meridian fibers of unequal length and taper (52 and 62% taper in width and 43 and 23% taper in thickness at respectively the ant. and post. ends in line suture lenses and only 30 and 43% and 27 and 41% reductions in the same parameters in Ysuture lenses) becoming arranged end–to–end as a number of suture branches to form concentric growth shells. The number and position of the suture branches is a consequence of fiber ends in these lenses curving a variable amount, 0–20 and 0–15o and 0–15 and 0–12o, respectively, anteriorly and posteriorly away from the polar axis in line and Y sutures. Thus, the ends of line and Ysuture lens fibers, blunt and box– like, cannot be readily displaced and replaced at suture branches to affect dynamic focusing.
Accommodative range in umbilical, line and Y suture lenses is related to lens architecture. Umbilical lenses have leaf spring–like fibers with pin shaped ends that are collectively displaced (interfaced at sutures) and replaced (returned to an end–to–end arrangement at sutures) in the accommodated and non–accommodated states. In contrast, non–primate lenses have simple coil fibers of variable diameter with blunt ends that preclude realignment of fiber ends for dynamic focusing.
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