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Myrto Korogiannaki, Michael Samsom, Tannin A Schmidt, Heather Sheardown; The Effect of Hyaluronic Acid on the Surface Properties of Recombinant Human Proteoglycan 4 modified Model Contact Lenses. Invest. Ophthalmol. Vis. Sci. 2017;58(8):3066.
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Contact lens-induced dry eye (CLIDE) remains a considerable burden in CL industry. Up to 50% of CL wearers experience symptoms of ocular dryness and discomfort, mainly attributed to poorly hydrated and lubricated surfaces and to biofouling, leading to discontinuation of use. Rewetting eye drops with wetting agents, such as hyaluronic acid (HA), are currently applied to counteract dryness. Proteoglycan 4 (PRG4) is a mucinous glycoprotein naturally found on the ocular surface acting as a boundary lubricant. A small clinical study showed that human recombinant PRG4 (rhPRG4) reduced effectively signs and symptoms of dry eye. HA and PRG4 can interact to synergistically reduce further friction. This work aims to examine the impact of HA sorption on the surface properties of rhPRG4 surface grafted model CLs.
The monomers 2-hydroxyethyl methacrylate (HEMA) and methacryloxypropyltris (trimethylsiloxy) silane (TRIS) were used for the synthesis of the model pHEMA and pHEMA-co-TRIS hydrogels. ATR-FTIR and XPS were used to confirm the surface grafting of full-length rhPRG4 on the examined materials via 1,1’-carbonyldiimidazole chemistry. Following, the samples were soaked in HA solution (1 MDa, 0.18%) for 12 hours. The impact of HA on the in vitro surface wettability (contact angle), friction (biomechanical testing, disc-cornea biointerface), protein deposition and dehydration rate (gravimetric analysis) was assessed.
Successful grafting of rhPRG4 on both surfaces was indicated by ATR-FTIR and XPS spectra. Lower contact angles were observed for rhPRG4-pHEMA-co-TRIS surfaces (p<0.002) only, while HA sorption decreased contact angles solely for rhPRG4-pHEMA (p<0.001). Using an artificial tear solution, HA further improved the antifouling proteins of rhPRG4-modified hydrogels against lysozyme and albumin (p<0.05). Under boundary lubrication conditions, HA was found to reduce synergistically with rhPRG4 the friction of pHEMA-co-TRIS hydrogels , whereas the friction for rhPRG4-pHEMA was increased (p<0.001). A reduction in dehydration rate for both materials was observed upon overnight soaking with HA (p<0.01).
The wetting and lubricating properties of HA in solution can be combined with the advantageous properties of rhPRG4 coating, especially for silicone hydrogel based contact lenses, to alleviate potentially the symptoms of ocular dryness and discomfort.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
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