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K.J. Al–Ghoul, S. Al–khudari, S.T. Donohue; Age–Related Compaction Affects Cortical Fiber Volume in Rabbit Lenses . Invest. Ophthalmol. Vis. Sci. 2005;46(13):2899.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: Our prior investigations have shown that compaction is correlated with increased scatter as a function of age in rabbit lenses. Structural data also indicated that age–related compaction in outer nuclear fibers preceded compaction in the inner fibers. Therefore this study was conducted to determine if significant fiber compaction occurred in the cortex. Methods:New Zealand White rabbits at 16–20 months old (adult) and 3.5–4 years old (aged) were utilized for this study. Immediately after sacrifice, scatter was assessed by laser scan analysis using the ScantoxTM In Vitro Assay System. Lenses were fixed, then dissected to obtain successive shells of cortical fibers. Straight fibers (lacking end–curvature) at 6 and 7 mm equatorial diameter were photographed and measured to determine fiber length, then processed and embedded for LM. Cross–sectional fiber area was measured in the equatorial segment using Scion Image (v. Beta 4.0.2). Estimates of fiber volume were made by multiplying fiber length by average cross–sectional area. Results: In adult lenses, the average cross–sectional area of fibers at 7 mm diameter was 33% smaller than at 6 mm diameter. Volume estimates showed a similar decrease of 30% from 6 to 7 mm. In aged lenses, there was a 48% decrease in the average cross–sectional area of fibers at 7 mm diameter as compared to those at 6 mm diameter. The volume of aged fibers decreased approximately 44% from 6 to 7 mm diameter. Thus, as expected, the older, more centrally located fibers were larger than younger, more peripherally located fibers in both adult and aged lenses. Comparisons between age groups revealed that at a diameter of 6 mm, the volume of aged fibers was 15% smaller than adult fibers. Furthermore, aged fibers at 7 mm diameter displayed a decrease in volume of 31% as compared to adult fibers at the same diameter. Conclusions: Cortical fibers in aged lenses had markedly reduced volume as compared to those in adult lenses, indicating a greater degree of compaction. In addition, it appears that younger, more peripheral fibers undergo more compaction than older, more central fibers in rabbit lenses. The data suggest that increased scatter in aged rabbit lenses is primarily due to cortical fiber compaction which may result from water loss and subsequent volume reduction.
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