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Danilo Aleo, Barbara Melilli, Maria Grazia Saita, Assunta Borzacchiello, Sergio Mangiafico, Melina Cro, Sebastiano Mangiafico; Hyaluronic Acid Preparation with Improved Corneal Wettability Property. Invest. Ophthalmol. Vis. Sci. 2017;58(8):487.
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© ARVO (1962-2015); The Authors (2016-present)
The wettablility of corneal surface is a very important characteristic of tear substitutes. It is usually obtained with the use of surfactants, substances with very poor ocular tolerability. The aim of our study was to develop a new association between hyaluronic acid (HA) and polivinylalcohol (PVA), polymer able to increase the wettability property of the HA formulation without modifying the rheological characteristics of HA.
Ophthalmic hypotonic (150 mOsm/l) preparation of HA 0.20% (SVS201) was added with 0.25% of PVA (MDV200). Corneal wettability property of the two formulations, MDV200 and SVS201, was evaluated by the measurement of contact angle conducted 5 times for each formulation as function of time by OCAE15 System. Comparison between MDV200 and SVS201 was done by evaluating the contact angle measured after 50 sec. Plexiglass and polyamide having a surface tension of 38-40mN/m were used as models of the corneal surface (40mN/m).Rheological characteristics were measured with Bohlin CVO Rehometer, using a cone-and-plate geometry (CP60/2); elastic modules (G’) and viscous modules (G’’) were evaluated as function of frequency, between 0.1-10.0Hz.
MDV200 and SVS201 maintained the same viscosity-shear rate dependence as well as the elastic (G’) and the viscous (G’’) modules, between 0.1-10.0Hz.MDV200 showed a very low contact angle (57°) when compared with the formulation without PVA (SVS201, 81°) when polyamide surface was used. When plexiglass was used, values were: MDV200 (64°) and SVS 201 (69°).
PVA was able to decrease the contact angle in the plexiglass surface as well as in polyamide. The effect was higher in polyamide than in plexiglass, they act like the cornea: are hydrophobic and have very similar surface tension. However, due to the presence of nitrogen and oxygen atoms in its molecular structure, polyamide acts more like the cornea and differently to the plexiglass. In other words polyamide is able, just like the corneal tissue, to interact with MDV200 through the formation of hydrogen bonds. We may then conclude that polyamide is better experimental model than plexiglass, and that MDV200, due to the presence of PVA, has a potential much higher corneal wettability (lower contact angle) than pure HA formulation (SVS201).
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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