Abstract
Purpose :
It has been shown that vitreous viscosity changes with age and these changes are highly correlated with retinal detachment. However, there is no non-invasive method to measure the viscosity clinically at the moment. We propose a novel non-invasive MRI-based viscometry method.
Methods :
Synthetic vitreous samples with various viscosities were prepared by mixing various concentrations of hyaluronic acid and agar (1:1 weight ratio). The rheological parameters – storage modulus (G'), loss modulus (G''), complex viscosity (η*) and consistency index (K) of these samples were measured using a Discovery HR-2 rheometer (TA Instruments, USA). A 3T clinical MRI (SKYRA, Siemens, Germany) equipped with a 16 channel knee coil was used to image samples. Transverse relaxation rates (R2) were processed from MR images using custom-built software. Clinical translation was attempted by measuring the same parameters of ex-vivo porcine eyes (n = 7).
Results :
MRI-measured of the synthetic vitreous samples correlated well with rheology-obtained parameters using exponential fits. Based on the measured MRI data of ex-vivo porcine vitreous and using the correlations obtained previously, a η*and K were predicted to be 2.37±0.40 Pa.s and 0.10±0.01, respectively. These values agreed with that of measured by rheology which were 2.34±0.59 Pa.s and 0.38±0.08, respectively.
Conclusions :
We have developed a non-invasive MRI-based viscometry technique, which has the potential of being implemented clinically. Our next step is to put our technique through a clinical trial to determine vitreous liquefactions involved in normal aging eyes and ocular pathologies.
This abstract was presented at the 2019 ARVO Imaging in the Eye Conference, held in Vancouver, Canada, April 26-27, 2019.