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P.D. Lamar, A.C. Acosta, W. Lee, F. Manns, M. Orozco, R. Augusteyn, A. Ho, S. Decker, B. Holden, J.–M. Parel; Zonular Architecture of the Crystalline Lens Examined ex vivo in a Lens Stretcher . Invest. Ophthalmol. Vis. Sci. 2005;46(13):737.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To assess physical changes in the zonular morphology in situ in disaccommodated and accommodated lens preparation. Methods: 19 human (55–91 y/o) and 19 Cynomolgus (3–7 y/o) fresh eyes were mounted on a 8–segment manual lens stretcher (Parel et al, ARVO 2004) and dissected to expose lens, zonules and ciliary body intact. Tissues underwent: 20x digital shadowphotogrammetry (Rosen AM et al, ARVO 2002); 5–40x optical anatomopathology microscopy (Denham et al ARVO 2004) and/or, (c) after fixation, dehydration and gold coating, scanning electron microscopy (10–10000x). To expose the posterior zonule, the first gold coating was pulled out removing remnant vitreous and hyaloid membrane and the specimen was gold coated again. Results: No zonular breakage could be detected in any of the eyes radially stretched to 2.5mm, corresponding to loads of 14 to 18g based on EVAS results (Parel et al, ARVO’2002). Trypan blue produced a higher zonule to capsule contrast than ICG. 75% of the tissues were lost during the SEM critical point drying process due to anterior capsule bursting. In all species, anterior zonules were thicker and more numerous than posterior zonules and both were taut when under tension whereas peripheral zonules were not. The anterior zonules encroached up to 2mm on the lens capsule of old human eyes whereas the posterior zonules were located within a <1mm wide peripheral annulus. The thickness of the anterior zonules was approximately 3 time the posterior zonules and >10x the equatorial zonules. The human zonule appearance, thickness and density were different than in monkeys. The number of SEM eyes was insufficient to assess the effect of stretching on the zonules diameter. Conclusions: Changes in zonular architecture can be quantified optically and histologically in post–mortem lenses during simulation of accommodation by stretching. Differences in the zonular anatomy between monkey and human lenses may affect the optomechanical response during stretching. Support: NIH EY14225; Florida Lions Eye Bank; Australian Government’s CRC Scheme; NIH center grant P30–EY014801; Research to Prevent Blindness; Henri and Flore Lesieur Foundation; N Kenyon PhD, P Gullett DVM, D Rothen DVM
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