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Stephen Davio, Megan Cavet, Karen Harrington, Amy Walsh, Zora Marlowe, Brian Glass, Paramita Sarkar; Corneal Epithelial Cell Protective and Wettability-enhancing Properties of Hyaluronic acid + PEG 8000 in an Artificial Tear Product. Invest. Ophthalmol. Vis. Sci. 2013;54(15):6000.
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© ARVO (1962-2015); The Authors (2016-present)
Artelac Rebalance® (“product”) is an artificial tear product which combines hyaluronic acid (HA) and a large molecular weight polyethylene glycol, PEG-8000. We conducted in vitro studies to probe the effect of this unique combination on corneal epithelial cell survival under desiccating stress. We also evaluated wettability aspects of the formulation using physical measurements.
Corneal cell survivability under desiccating stress was evaluated using human corneal epithelial cells (HCEpiC) pre-treated with saline (control) or 50% product +/- HA and +/- PEG 8000 for 10 min followed by desiccation for 20 min. The percentage of living cells was determined by staining with calcein using the LIVE/DEAD assay kit (Invitrogen). Wettability of the formulation was assessed for product +/- HA and +/- PEG 8000 by measuring surface tension (Kruss K-100) and by measuring the effect of the formulation on contact angle in a captive bubble apparatus (FTA 1000 + FTA32 video 2.0 software) using a silicone hydrogel contact lens as model for the cornea. Contact angles were measured in the presence of the product, and after removal of product and replacement with saline.
Corneal cells exposed to product show significantly higher survival to desiccating stress than cells exposed to saline (68 and 72% vs. 5%, respectively). Removal of HA from the formulation drops cell survivability to that of the saline control. Removal of PEG-8000 has no effect on cell survivability which remains equivalent to intact formulation. Surface tension (ST) measurements on the intact formulation show 64 mN/m which is a decrease from that of water, 72 mN/m. This effect is entirely associated with PEG 8000. Contact angle measurements using the captive bubble apparatus show the product enhances the wettability of a model surface which persists after replacement of the product with saline. This enhanced wettability and the residual effect are both due exclusively to PEG 8000.
The in vitro and physical measurements demonstrate complementary properties of HA and PEG 8000 in the artificial tear product. HA is demonstrated to enhance survival in corneal cells under desiccating stress. PEG 8000 demonstrates a consistent decrease in surface tension and an ability to enhance the wettability of a model surface which persists after removal of the product.
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