School of Mechanical Engineering, Shiraz University, Shiraz, Iran.
Med Eng Phys. 2012 Jul;34(6):681-92. doi: 10.1016/j.medengphy.2011.09.011. Epub 2011 Oct 19.
In this study, the flow dynamics of vitreous due to saccadic movements following vitreous liquefaction or in post-vitrectomy eyes is investigated. Using a dynamic mesh technique, the eye motion was modeled and unsteady three-dimensional forms of continuity and Navier-Stokes equations were solved numerically. Firstly, the numerical model was validated for a sphere as a model of vitreous chamber and agrees well with the results based on available analytic solutions and experimental data. Then, numerical simulation was performed based on a deformed sphere with an indentation representing the lens. This consists of a vitreous cavity filled with a liquid having the viscosity of liquefied vitreous and balanced salt solution. The wall shear stress on the retina was computed and compared for various saccade amplitudes. Also, the effect of variation in vitreous viscosity and the size of lens indentation are investigated. The results show that the secondary flow in the vertical direction in the vitreous cavity is much higher for the liquefied vitreous and balanced salt solution compared with that for silicone oil. The possible effect of shear stress on the retinal detachment for all studied cases is discussed. A semi-analytic correlation is also developed for maximum wall shear stress of the spherical domain that is subjected to sinusoidal rotations.
本研究旨在探讨玻璃体液在玻璃体液液化或玻璃体切除术后眼内的眼球跳动运动中的流动动力学。采用动态网格技术对眼球运动进行建模，并对非定常三维连续性方程和纳维-斯托克斯方程进行数值求解。首先，通过将玻璃体腔简化为球体来验证数值模型，结果与基于现有解析解和实验数据的结果吻合良好。然后，基于具有代表晶状体的凹陷的变形球体进行数值模拟，该球体由充满具有液化玻璃体粘度的液体和平衡盐溶液的玻璃体腔组成。计算并比较了视网膜上的壁面剪切应力在各种眼球跳动幅度下的变化。此外，还研究了玻璃体粘度和晶状体凹陷大小的变化对结果的影响。结果表明，与硅油相比，液化玻璃体和平衡盐溶液在玻璃体腔内的垂直方向上的二次流要高得多。还讨论了所有研究案例中剪切应力对视网膜脱离的可能影响。此外，还针对受正弦旋转作用的球形域的最大壁面剪切应力开发了一种半解析相关性。
