Measurements of retinal viscoelasticity using acoustic radiation force optical coherence elastography

The viscoelasticity of the retina can reflect its function and state. Accurate assessment of retinal viscoelasticity can assist in early diagnosis of retinal diseases. With high-resolution and non-contact features, optical coherence elastography (OCE) has been used to evaluate the retinal elasticity based on the elastic wave velocity measurement. Nonetheless, the retinal viscosity cannot be assessed. In this study, a shear wave dispersion OCE method was proposed to measure the retinal viscosity and elasticity. After acoustic radiation force (ARF) induces a shear wave, optical coherence tomography (OCT) visualizes shear wave propagation in the retina. The wave velocities at different frequencies are analyzed, and the viscoelasticity is quantified based on the dispersion analysis. The accuracy of the method was verified on phantoms with different glycerol concentrations. The viscosity of the phantom is related to the concentration of glycerin, and its elasticity is adjusted by the agar concentration. The OCE results closely matched the elasticity measured by a mechanical testing system. Furthermore, the retinal shear wave velocity dispersion on the ex-vivo porcine eye was analyzed to determine its viscoelasticity. Our results demonstrate that ARF-OCE can quantitatively evaluate the viscoelasticity of the retina. The shear wave dispersion OCE method has great potential for diagnosing retinal diseases.