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D. Borja, F. Manns, S. Uhlhorn, A. Ho, J.-M. Parel; Age-Dependent Optical Model of the Isolated Human Crystalline Lens. Invest. Ophthalmol. Vis. Sci. 2009;50(13):6125. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
To determine the age-dependence of the shape and optical power of the isolated human crystalline lens. The isolated lens with no zonular tension applied corresponds to the maximal possible state of accommodation.
The shape and power of 130 isolated lenses from 84 Eye-Bank donors were measured (ages 6 to 94 years, average = 51.1±19.3 years, pmt = 2.75±1.5 days). The isolated lens thickness, diameter, and anterior and posterior curvature and asphericity, were extracted from undistorted shadowphotographs of the lens contour. Optical power was obtained with a modified lensmeter (Lens Analyzer 350, Zeiss Humphrey, Dublin, CA). The measured data of each eye was entered in an optical ray tracing software (OSLO LT, Lambda Research, Littleton, MA) to determine the equivalent refractive index and the relative contributions of the index gradient to the total lens power. A statistical analysis using non-linear regression was performed on each measured and calculated optical and biometric parameter to produce an age-dependent optical model.
Non-linear age-dependencies were observed for all measured parameters with breakpoints occurring around the age of presbyopia onset depending on the parameter (50-58 years). Before the breakpoint age, lens diameter increased at +0.04mm/year , thickness decreased at -0.04mm/year (up to 27 years), anterior and posterior surfaces flattened at 0.14 and -0.06 mm/year respectively, total power decreased at -0.41D /year, equivalent index decreased by -3.9x10-3/year, surface contribution increased by 0.17%/year. After the breakpoint, central thickness increased (after 27 years), surface curvatures steepen and total refractive power increased slightly.
The normal age-related growth of the lens has a de-accommodating effect on the shape and power of the lens. These results suggest that, independent of the response of the lens to zonular tension, the changes induced by lens growth alone may significantly contribute to the loss of accommodation amplitude with age.Support: 2R01EY14225; 5F31EY15395 (DB); F32EY15362 (SU), Florida Lions Eye Bank; P30EY14801 Center Grant; Research to Prevent Blindness; Vision CRC, Sydney, supported by the Australian Federal Government through the Cooperative Research Centres Programme; the Henri and Flore Lesieur Foundation (JMP).
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