Purchase this article with an account.
Alyssa Lesley Lie, Xingzheng Pan, Thomas William White, Paul J Donaldson, Ehsan Vaghefi; Age-dependent changes to the free and total water distribution of the in vivo human lens measured by MRI. Invest. Ophthalmol. Vis. Sci. 2021;62(8):2095.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
To use magnetic resonance imaging (MRI) to noninvasively measure changes in steady-state free and total water gradients in human lenses in vivo with advancing age.
57 subjects aged 18 to 86 years were recruited under approval from the University of Auckland Human Subjects Ethics Committee (#017162), fitted with a 32-channel head receiver coil and placed in a 3 Tesla clinical MR scanner. MRI scans of the crystalline lens were obtained using a volumetric interpolated breath-hold examination (VIBE) sequence with dual flip angles, then corrected for field inhomogeneity post-acquisition with a B1-map obtained using a TurboFLASH sequence. Corrected lens free water (T1) and total water (PD) maps were then calculated using an established MRI signal equation (Blüml et al., 1993; Deoni et al., 2003). PD values were normalised to an external water reference included in the scanner. Free and total water profiles along the lens optical axis were extracted using MATLAB custom-written software and the age-dependent changes in parameters determined by linear regression.
No significant changes to either the profile shape or amount of total water in different regions of the lens was observed with age (all p > 0.05). Unlike total water, which was linearly distributed across the lens, a gradient in free water that was highest in the periphery and lowest in the central region was observed in all lenses. However, with advancing age, this free water gradient collapsed from an initial parabolic shape in young lenses to one with an enhanced central plateau in older lenses, as indicated by significant increases in the values of the profile shape parameter with age (anterior: 0.067/year, p = 0.004; posterior: 0.050/year, p = 0.020). Furthermore, with advancing age a significant increase in central free water content was also observed (1.932 ms/year, p = 0.022).
MRI can successfully map free and total water distributions of in vivo human lenses. The observation that the steady-state free, but not total, water gradient of the lens collapses with age raises the possibility that age-dependent changes to the way lens proteins bind water is an underlying cause of changes to lens optics and therefore overall vision that is observed as we age.
This is a 2021 ARVO Annual Meeting abstract.
This PDF is available to Subscribers Only