Ultrahigh field MRI determination of water diffusion rates in ex vivo human lenses of different age

Background: The development of presbyopia is correlated with increased lens stiffness. To reveal structural changes with age, ultrahigh field magnetic resonance imaging (UHF- MRI) was used to analyze water diffusion in differently aged human lenses ex vivo. Methods: After enucleation lens extractions were performed. Lenses were photographed, weighed, and embedded in 0.5% agarose dissolved in culture medium. UHF-MRI was conducted to analyze anatomical characteristics of the lens using T2-weighted Turbo-RARE imaging and to obtain apparent diffusion coefficients (ADC) measurements. A Gaussian fit routine was used to examine the ADC histograms. Results: An age-dependent increase in lens wet weight, lens thickness, and lens diameter was found (P<0.001). T2-weighted images revealed a hyperintense lens cortex and a gradually negative gradient in signal intensity towards the nucleus. ADC histograms of the lens showed bimodal distributions (lower ADC values mainly located in the nucleus and higher ADC values mainly located in the cortex), which did not change significantly with age [beta Peak1=1.96E-7 (-20E-7, 10E-7), P=0.804 or beta Peak2=15.4E-7 (-10E-7, 40E7), P=0.276; respectively]. Conclusions: Clinically relevant age dependent lens hardening is probably not correlated with ADC changes within the nucleus, which could be confirmed by further measurements.

Automated summary

The development of presbyopia is associated with increased lens stiffness, but age-dependent changes in lens structure were not found to correlate with ADC values. The study suggests that further measurements are needed to confirm the lack of correlation between lens hardening and ADC changes.