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Meng C Lin, Tatyana F Svitova; Can OTC artificial tears ophthalmic solutions stabilize tear film? An in vitro study.. Invest. Ophthalmol. Vis. Sci. 2018;59(9):3825.
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© ARVO (1962-2015); The Authors (2016-present)
To evaluate the efficacy of current popular OTC artificial tears formulations in water-evaporation retardation and assess the influence of these formulations on dynamic interfacial properties of model tear lipids (MTL).
Tensiometry, in sessile-drop configuration with precise drop-volume control, was used to quantify the water-evaporation rates at constant 36°C temperature and humidity RH = 75%. 8-10 µl drops of liquids were formed and kept in sealed optical cell for 24-48 hours. The measurements of the dynamic surface pressure were performed under the same conditions. The OTC formulations tested were: Lipomist, Purcell, Thealoz Duo, Diquas, Retain MGD, Soothe XP, Refresh Optive Mega-3, along with 80-nm thick layers of Castor and Flaxseed oils on model tear electrolyte solution (MTE). The 70-80 nm-thick layers of MTL (85% of nonpolar lipids, 15% of polar lipids) were deposited on freshly-formed surface of each dry-eye formulation drops, and as control on the surface of MTE drops
Aged MTL films reduced water-evaporative flux by 60±6%. For OTC formulations, the highest reduction by 43±5%,and the lowest, by 10±4%, were observed for Refresh Optive and Theloze, respectively. Refresh Optive and pure Flaxseed oil films had similar flux (p =0.018). For other formulations, the evaporative flux reductions were between 10-43%. MTL films spread atop OTC drops reduced evaporative flux by additional 10±5%, however, these fluxes remained higher than of MTL alone by 9±3% (p=0.012). Diquas, Refresh Optive, and Soothe drops with 75 nm-thick MTL films had shown dynamic interfacial behaviors noticeably different from MTL. Diquas made MTL film more rigid, with substantial hysteresis. The components of Refresh caused liquefying of MTL films. The most noticeable alterations were caused by Soothe, it decreased maximum surface pressure by 8±2 mN/m and distorted MTL interfacial pressure dynamics.
For the first time, our in vitro study of water-evaporation retardation by OTC ophthalmic drops has demonstrated that these formulations can reduce water-evaporation fluxes due to the presence of Flaxseed oil or other additives. However, none of these OTC formulations enhanced or reached the level of MTL evaporative resistance. Some drops caused strong alterations of tear-lipid layer interfacial dynamic properties, which may lead to tear-film destabilization in vivo.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
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