Wow, it's already more than halfway through January within the new year. Time really does fly, huh? We hope that 2018 has been good and already have been a learning experience so far.
For many of us, everyday is a new venture of exploring different opportunities to either learn or discover new concepts and applications. Among our most recent publications, Dr. Stacey Elliott pokes at the importance of viscosity and its shear rate dependence on the performance of eye drops, specifically those formulated for the relief of dry eye. The argument is, "Since an adequate amount of product must remain in the eye to provide any benefit, the first performance factor is the fluid volume or film thickness retained at the time of application."
By sampling different eye-drop brands, we were able to formulate non-Newtonian viscosity versus shear rate data for each brand by using the Carreau-Yasuda model, or via the Cross model. Since the surface of the eye is a concave fixture, it is really interesting to observe how much of the actual eye drop mixture is retained as the eye blinks, and to what extent shear thinning factors attribute to the composition of the eye-drops itself.
Viscosity vs shear rate for listed products (view full data in application note)
For more information, join us for part 1 of our series to see the importance of fluid retention at insertion by clicking here and explore our application notes.
Feel free to reach out to us if you have any questions or comments regarding any of our applications or just want to chat!