Back to Journals » Clinical Ophthalmology » Volume 11

Investigating the potential benefits of a new artificial tear formulation combining two polymers

Authors Simmons PA, Vehige JG

Received 24 February 2017

Accepted for publication 26 July 2017

Published 12 September 2017 Volume 2017:11 Pages 1637—1642


Checked for plagiarism Yes

Review by Single anonymous peer review

Peer reviewer comments 2

Editor who approved publication: Dr Scott Fraser

Peter A Simmons, Joseph G Vehige

Allergan plc, Irvine, CA, USA

Artificial tear formulations typically contain a water-soluble polymer to enhance residence time, moisture retention, and binding to the mucin coat of the ocular surface, which facilitate corneal healing. This study investigated the potential advantages of combining carboxymethylcellulose (CMC) and hyaluronic acid (HA) polymers in a single formulation.
Materials and methods: Individual CMC and HA solutions were prepared and tested for bulk viscosity in comparison to a solution that combined CMC and HA. Rheometry determined the differences between solutions at increasing shear rates, simulating eye movement and blinking.
Results: The bulk viscosity of the individual 0.5% CMC and 0.1% HA solutions was 2.5 and 5.7 cP, respectively. The viscosity of the combined solution (13.1 cP) was 60% higher than predicted by additive effects. Rheometry revealed shear rates between 10/second (open eye) and 10,000/second (blinking eye). At these rates, viscosity ranged from 2.7 to 3.5 cP for 0.5% CMC, 2.8 to 6.8 cP for 0.1% HA, and 5.2 to 15.3 cP for the 0.5% CMC–0.1% HA combination. Low-shear viscosity of the CMC–HA combination increased 48% over the sum of the individual solutions, but high-shear viscosity remained virtually unchanged. Data from CMC and HA solutions at higher concentrations were consistent with these results.
Conclusion: Combining CMC and HA polymers produced a synergistic increase in low-shear viscosity (which cannot be fully explained by simple molecular entanglement), while the high-shear viscoelasticity of the combined solution remained unaffected. These data suggest that CMC–HA combinations have properties that may be used to formulate artificial tears that optimize ocular retention (through higher low-shear viscosity), while minimizing blur and stickiness during blinking (through lower high-shear viscosity).

artificial tear, eyedrop, dry eye, carboxymethylcellulose, hyaluronic acid

Creative Commons License This work is published and licensed by Dove Medical Press Limited. The full terms of this license are available at and incorporate the Creative Commons Attribution - Non Commercial (unported, v3.0) License. By accessing the work you hereby accept the Terms. Non-commercial uses of the work are permitted without any further permission from Dove Medical Press Limited, provided the work is properly attributed. For permission for commercial use of this work, please see paragraphs 4.2 and 5 of our Terms.

Download Article [PDF]  View Full Text [HTML][Machine readable]