MICRO AND NANO LUBRICANT BEHAVIOR OF TEAR FILM AQUEOUS LAYER
DOI:
https://doi.org/10.7251/COM1201055BAbstract
Tears provide moisture and supply oxygen and other important nutrients to the cornea, mechanically trap and flush out foreign bodies and chemicals and keep the surface of cornea smooth and optically clear. Additionally, during blinking, tear film lubricates the friction area between lids and ocular surface. Tear film contains an aqueous layer that includes water, bacteriostatics, proteins and salt. Contact lens wearers often suffer from dry eyes. These changes in the tear film are caused by contact lens design, surface, material and applied solution for conditioning. In case of application of gas-permeable contact lens, the multi-factorial problem of tear film stability and therefore, maintaining of lubrication are main goals in the ongoing investigation. This paper focuses on applied research of the response of material’s surface roughness quality to retain tear film on the micro and nano-level by using a gliding-box method for lacunarity analysis. The topology of contact lens surface with tear film as the lubricant was studied from the point of view of the water as primary consistent in its bulk liquid form, as well as confined water film organized into layers in a nanometer-sized channel. Contact lens surface topology observed on micro and nano-scale indicates different lubrication behavior of aqueous tear layer. As opposed to bulk water as a disordered medium in micro scale that flows very readily, nano-water demonstrates the behavior effectively like some phases of liquid crystals.References
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[4] H. Kyakuno, K. Matsuda, H. Yahiro, et al., Confined water inside single-walled carbon nanotubes: Global phase diagram and effect of finite length, The Journal of Chemical Physics, 134 (2011) 244501(1)−(14).
[5] F.Wang, Y.Zhao, Tehnique properties of the solid-like confined liquid films: A large scalemolecular dynamics simulation approach, Acta Mechanica Solida Sinica, 24−2 (2011) 101−116.
[6] B. Mandelbrot, The Fractal Geometry of Nature, W.H. Freeman and Co, New York, 1982.
[7] R. Voss, Random fractals: characterization and measurement, Scaling phenomena in disordered systems, 10−1 (1986) 51–61.
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[10]http://wiki.answers.com/Q/Width_of_a_water_molecule#ixzz1T8WDNrE4.
[11]http://www.btinternet.com/~martin.chaplin/interfac2.html.
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2012-10-19
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