Coefficient of friction values may aid contact lens development - Healio

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Coefficient of friction values may aid contact lens development
[SIZE=-1]Healio[/SIZE]
[SIZE=-1]Researchers have measured the coefficient of friction value on human corneal tissue, providing a method of evaluating the ability of a contact lens to mimic the natural ocular environment, according to a press release from Vistakon Division of Johnson ...[/SIZE]
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[SIZE=-1]http://news.google.com/news/more?ncl=d49mUTHLmNG4xnM&ned=us[/SIZE]

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[Greg Gemoules]

About time, IMHO.

 

[Gary R. Bell]

I'm confused by this article. As far as I know, the coefficient of friction applies when rubbing one solid surface upon another. These criterion do not apply to the eye and soft contact lens applications.

In the case of the corneal environment, you are dealing with liquid (the tear film, which is a multi-layer visco-elastic liquid), and the visco-elastic cornea and C.L. In such environments, the measurement of friction is not used. The proper measurement is viscous drag, which is a variable of the off-setting forces of molecular cohesion, and adhesion. At the very least, lubrication theory should be used to make sense of such an environment, or full application of fluid dynamic principles.

Either J&J is dumbing down the press release because they know O.D.'s are not up to speed on fluid dynamics, or they are totally off base.

 

[Greg Gemoules]

I'm confused by this article. As far as I know, the coefficient of friction applies when rubbing one solid surface upon another. These criterion do not apply to the eye and soft contact lens applications.

In the case of the corneal environment, you are dealing with liquid (the tear film, which is a multi-layer visco-elastic liquid), and the visco-elastic cornea and C.L. In such environments, the measurement of friction is not used. The proper measurement is viscous drag, which is a variable of the off-setting forces of molecular cohesion, and adhesion. At the very least, lubrication theory should be used to make sense of such an environment, or full application of fluid dynamic principles.

Either J&J is dumbing down the press release because they know O.D.'s are not up to speed on fluid dynamics, or they are totally off base.

Heh, maybe you should get in touch with them. Maybe they could use your expertise. They do indicate in the article that maybe this was just some kind of preliminary experiment. Anyway, it is nice to see the companies are devoting more time to studying the surfaces and trying to improve them.

Back in 2003 I did some study with different polymers on their dehydration characteristics and water content. The University of Dallas analytical chemistry department let me use their lab.

In the process of doing research for my talk, I ran across this paper that presented a technique for applying a phosphorylcholine coating to a silicone or silicone-hydrogel lens and was always intrigued with that kind of stuff, but difficult to do in your garage.

Now we have the new, lubricious Dailies Total 1. I look forward to the next revolution in lenses since the introduction of SiHy.