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Tear-film breakup: The role of membrane-associated mucin polymers
Physical Review E ( IF 2.2 ) Pub Date : 2021-01-20 , DOI: 10.1103/physreve.103.013108
Anjishnu Choudhury 1 , Mohar Dey 2 , Harish N Dixit 3 , James J Feng 4
Affiliation  

Mucin polymers in the tear film protect the corneal surface from pathogens and modulate the tear-film flow characteristics. Recent studies have suggested a relationship between the loss of membrane-associated mucins and premature rupture of the tear film in various eye diseases. This work aims to elucidate the hydrodynamic mechanisms by which loss of membrane-associated mucins causes premature tear-film rupture. We model the bulk of the tear film as a Newtonian fluid in a two-dimensional periodic domain, and the lipid layer at the air-tear interface as insoluble surfactants. Gradual loss of membrane-associated mucins produces growing areas of exposed cornea in direct contact with the tear fluid. We represent the hydrodynamic consequences of this morphological change through two mechanisms: an increased van der Waals attraction due to loss of wettability on the exposed area, and a change of boundary condition from an effective negative slip on the mucin-covered areas to the no-slip condition on exposed cornea. Finite-element computations, with an arbitrary Lagrangian-Eulerian scheme to handle the moving interface, demonstrate a strong effect of the elevated van der Waals attraction on precipitating tear-film breakup. The change in boundary condition on the cornea has a relatively minor role. Using realistic parameters, our heterogeneous mucin model is able to predict quantitatively the shortening of tear-film breakup time observed in diseased eyes.

中文翻译:


泪膜破裂:膜相关粘蛋白聚合物的作用



泪膜中的粘蛋白聚合物可保护角膜表面免受病原体侵害并调节泪膜流动特性。最近的研究表明,在各种眼部疾病中,膜相关粘蛋白的丢失与泪膜过早破裂之间存在关系。这项工作旨在阐明膜相关粘蛋白的损失导致泪膜过早破裂的流体动力学机制。我们将大部分泪膜建模为二维周期域中的牛顿流体,将空气-泪液界面处的脂质层建模为不溶性表面活性剂。膜相关粘蛋白的逐渐丧失导致与泪液直接接触的裸露角膜区域不断增大。我们通过两种机制表示这种形态变化的流体动力学后果:由于暴露区域润湿性的丧失而导致范德华吸引力的增加,以及边界条件从粘蛋白覆盖区域的有效负滑移到无粘蛋白覆盖区域的变化。暴露角膜上的滑动情况。有限元计算,使用任意拉格朗日-欧拉方案来处理移动界面,证明了升高的范德华引力对促进泪膜破裂的强烈影响。角膜边界条件的变化的作用相对较小。使用实际参数,我们的异质粘蛋白模型能够定量预测患病眼睛中观察到的泪膜破裂时间的缩短。
更新日期:2021-01-20
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