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R. K. Balachandran, V. H. Barocas; Computational Fluid Dynamics of Vitreous Humor During Saccadic Movements. Invest. Ophthalmol. Vis. Sci. 2008;49(13):1822.
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To predict the motion of vitreous humor during saccade and its effect on transport of drugs in the vitreous.
A three-dimensional finite-element model of the vitreous was constructed assuming that the vitreous is a Newtonian fluid. The boundaries of the model were the retinal surface, lens, and hyaloid membrane. Two studies were conducted. The first model consisted of three steps, following the experimental work of Walton et al.(Exp. Eye. Res 74: 173-180, 2002). The domain was rotated 45° to the left, then 90° to the right, then 45° to the left to return to the initial position. The motion of the vitreous was simulated for various viscosities to facilitate comparison with the experimental results of Walton et al. In the second study, a 40° amplitude sinusoidal oscillation was imposed, and the resulting flow profile was used to predict enhanced transport of drugs.
Simulations showed significant sloshing of the vitreous, especially at lower viscosities, demonstrated by three-dimensional vortices and by overshoot of the vitreous relative to the retina. Further, as expected, increased motion led to increased mass transport.
Although simulating the experiment is difficult, it is possible to estimate vitreous viscosity based on the model results and experimental studies of vitreous sloshing. Since transport is increased in the liquefied vitreous, care must be taken in predicting drug delivery to humans (often with liquefied vitreous) based on studies in animals (usually with intact vitreous).
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