Article

Anisotropic water transport in the human eye lens studied by diffusion tensor NMR micro-imaging.

Centre for Medical, Health and Environmental Physics, Queensland University of Technology, GPO Box 2434, Brisbane, Queensland, 4001, Australia
Experimental Eye Research (impact factor: 3.26). 07/2002; 74(6):677-87. pp.677-87
Source: PubMed

ABSTRACT We report in vitro measurements of effective diffusion tensors characterising the anisotropic transport of water in human eye lenses ranging in age from 13 to 86 years. The measurements were obtained by means of a pulsed field gradient spin echo (PFGSE) magnetic resonance imaging (MRI) technique at a spatial resolution of 218 x 218 x 1000 microm(3). The results show that water diffusion is both spatially inhomogeneous and highly anisotropic on the timescale of the measurements (approximately 15 msec). Diffusion parallel to the long axes of the lens fibre cells is relatively unrestricted, whereas that between cells is substantially inhibited by the cell membranes, particularly in the inner cortex region of the lens. The data confirm the presence of a diffusion barrier surrounding the lens nucleus, which inhibits transport of water and other small molecules into and out of the nucleus. The results shed light on factors that may influence the onset of presbyopia and senile cataract. They also have implications for delivery of drugs to the lens nucleus.

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Keywords

anisotropic
 
anisotropic transport
 
diffusion barrier
 
Diffusion parallel
 
drugs
 
effective diffusion tensors characterising
 
factors
 
human eye lenses
 
inhibits transport
 
inner cortex region
 
lens fibre cells
 
measurements
 
pulsed field gradient
 
senile cataract
 
small molecules
 
spatial resolution
 
spatially inhomogeneous
 
timescale
 
vitro measurements
 
water diffusion