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Thomas Stahnke, Rudolf F Guthoff, Oliver Stachs, Andreas Wree, Anselm G M Juenemann, Niels Grabow, Tobias Lindner, Stefan Polei; Ultra high-field MRI determination of diffusion rates in human lenses of different ages. Invest. Ophthalmol. Vis. Sci. 2017;58(8):2711.
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© ARVO (1962-2015); The Authors (2016-present)
Accommodation loss affects clinically every human individual older than 45. This effect is predominantly caused by increased lens stiffness. The aim of this investigation was to analyze effects in presbyopia in human lenses of different ages ex vivo using ultra high-field magnetic resonance imaging (UHF-MRI).
After enucleation intracapsular lens extractions were performed. Optically clear lenses (N=23) were photographed, weighed, and embedded in cooled 0.5% agarose solved in culture medium. UHF-MRI (7 Tesla, BioSpec 70/30, Bruker, Germany) was conducted to analyze anatomical characteristics, equatorial lens diameters and thicknesses in the central layer of each lens using T2-weighted Turbo-RARE sequences (Resolution: (75x75x800) µm3). Spin-echo based diffusion sequences (6 directions, 4 b-values between (100-1000) s/mm2) were used to obtain Apparent Diffusion Coefficient (ADC) values. A simple (double-) Gaussian fit routine was applied in order to examine two individual modes.
There was an age-dependent increase in lens weight, which was from 0.18 g for younger lenses (31-40 years) to 0.28 g for older lenses (81-90 years). In T2-weighted images the measured increase in lens diameter from 8.57 to 9.74 mm and in lens thickness (3.71 to 5.65 mm) was also age-related. Additionally, T2-weighted images revealed a hyperintense area of the lens cortex, which decreased in signal intensity stepwise towards the nucleus. Histogram analysis of the ADC values of individual lenses showed occurrence of bimodal distributions. Peak positions of the first mode (lower ADC values) in the ADC histogram appear to remain constant (~0.5*10-3 mm2/s), whereas for the second mode peak positions tend towards lower ADC values with increasing age.
Ex vivo UHF-MRI allowed detailed examinations of anatomical characteristics and diffusion coefficients of human lenses. In conjunction with the local distribution of ADC values within the lens the results indicate that the first mode represents mainly the lens nucleus where there was no change, whereas there is an age dependent decrease in the cortex region of the lens, represented by the second mode. Age dependent space-resolved ADC values showed unexpected alterations only in the cortical areas, the clinically obvious age dependent hardening of the nucleus is not correlated with changes in the Apparent Diffusion Coefficient.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
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