Purpose: Commonly cited reasons for high rates of dropouts in contact lens wearers in many studies are dryness and discomfort. Effectively reducing these symptoms may result in better patient outcomes. Wearer comfort has been shown to have a direct correlation to friction experienced by the user. It is believed that improving the lubricity of contact lenses, or minimizing the friction coefficient between the lens and the ocular surface, can significantly relieve dryness and discomfort. We developed two scalable approaches to fabricate innovative ultra-lubricious contact lenses. Methods: The basis of the first approach is polymerizing a thin film of N, N-dimethylacrylamide (DMA) on the surface of commercial lenses. DMA monomer is added to an aqueous solution along with one of the components of a redox pair ammonium persulfate (APS) for initiation of polymerization. The other component, N, N, N′, N′-Tetramethylethane-1, 2-diamine (TEMED) is loaded in the lens by soaking. Contact between TEMED and APS leads to rapid generation of free radicals that cause polymerization of DMA. The thickness of the layer depends on the polymerization time. In the second approach, we load the lens with a hydrophobic thermal initiator, Azobisisobutyronitrile (AIBN). It is then soaked in DMA solution at high temperatures to polymerize the surface film. Because the initiator is restricted to the lens, the DMA is polymerized only near the surface and inside the lens. The lubricious lenses were characterized to determine the surface thickness, chemical composition, water content, and friction coefficient in contact with a rabbit cornea. Results: FTIR confirms that DMA was polymerized into poly-DMA on the lens, creating a lubricious layer. The optimized process results in a 2.1±1.4 µm thick layer on each surface, or about 4% of the total lens thickness. The water content of the surface layer is ~285% and water contact angle has decreased from 93.7° to 20°. The friction coefficient of the surface is significantly lower. Conclusions: The modified lenses exhibit reduced contact angle and lower friction coefficient which suggests improved wettability and lubricity. Many selected brands of commercial lenses were modified successfully. The process is easy to control, and can be commercialized at a very low cost. The improved wettability and lubricity of the modified contact lenses may be beneficial to the lens wear comfort, which may lead to a reduction of contact lens wearer dropouts.

Interfacial polymerization of a thin lubricious film for improving wettability and lubricity

2019 Fall National Meeting

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