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Viscosity of tear solutions varies
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A lab study mimicking conditions in the eye found that a carboxymethylcellulose artificial tear solution maintained higher viscosity than two other tear products. The study was presented in a poster at the American Academy of Optometry meeting last month.
According to the authors, the study emphasizes the importance of the conditions under which viscosity is measured.
Peter Simmons, PhD, FAAO, and Joseph Vehige, OD, of Allergan’s Eye Care Clinical Research, attempted to recreate the physiological conditions of the eye to compare the viscosity of three tear preparations: a carbomer-based gel, a 1% carboxymethylcellulose-based product and a 0.18% guar gum-based product.
Mixing of the products with tear electrolytes and increasing the temperature to 35· C caused the carbomer gel to solubilize, reducing viscosity to 5 cps at low shear. The carboxymethylcellulose product was affected by dilution but not by electrolytes, with a viscosity of 8 cps at low shear. The guar-gum product was affected by dilution only, with a viscosity of 5 cps at low shear.