Department of Chemical and Biomolecular Engineering, University of California, Berkeley, CA 94720-1462, USA.
Cont Lens Anterior Eye. 2012 Dec;35(6):260-5. doi: 10.1016/j.clae.2012.07.003. Epub 2012 Jul 26.
In addition to improving oxygen permeability, modern silicone-hydrogel (SiHy) soft contact lenses (SCLs) exceed a limiting diffusive ion permeability to aqueous sodium chloride. Below the ion-permeability threshold, siloxane-based SCLs are prone to bind against the corneal epithelium. Salt permeability is argued to reflect indirectly water hydraulic permeability. However, no quantitative explanation is available to date for a threshold salt permeability. We hypothesize that molecular salt diffusion through a SCL supports the postlens tear film (PoLTF) by enhancing water flow into the PoLTF from the cornea. Higher salt concentrations in the PoLTF raise the osmotic pressure there relative to that in the cornea increasing osmotic water withdrawal from the cornea. The proposed osmotic-withdrawal mechanism successfully predicts a self-consistent threshold lens salt permeability when thin-film attractive binding forces are introduced. For the first time, we present a quantitative picture for the possible origin of a threshold salt permeability in SCL manufacture.
除了提高氧气透过率外，现代硅水凝胶（SiHy）软性隐形眼镜（SCL）的扩散离子透过率超过限制的氯化钠水溶液。在离子透过率阈值以下，基于硅氧烷的 SCL 容易与角膜上皮结合。有人认为盐透过率反映了水液压透过率的间接情况。然而，目前还没有定量解释盐透过率阈值的方法。我们假设，通过 SCL 的分子盐扩散通过增强水从角膜流入后泪膜（PoLTF）来支持后泪膜（PoLTF）。PoLTF 中的盐浓度升高会增加 PoLTF 中的渗透压，从而增加渗透压从角膜提取水。当引入薄膜吸引力结合力时，所提出的渗透压提取机制成功地预测了一致的阈值透镜盐透过率。我们首次提出了一个定量的图片，可能的起源的阈值盐透过率在 SCL 制造。
