Abstract
Purpose :
A new silicone hydrogel (SiHy) material with surface modification of a cross-linkable bioinspired 2-methacryloyloxyethyl phosphorylcholine (MPC) polymer was developed for outstanding ocular performance. The purpose of this study was to characterize the lens in fully hydrated conditions for its unique surface structure and properties, which are expected to contribute to the enhanced on-eye comfort and tear film stability of this novel contact lens.
Methods :
The surface structure of MPC polymer gel layer was imaged using a combination of environmental scanning electron microscopy (ESEM) and atomic force microscopy (AFM). The surface softness and lubricity of this new SiHy vs. comfilcon A, senofilcon A, and senofilcon C contact lenses were characterized via AFM nanoindentation and tribometer, respectively. All analyses were conducted in either 100% relative humidity or aqueous solutions to maintain lenses at hydrated state, mimicking on-eye conditions.
Results :
A distinctive layer of hydrated MPC polymer was clearly visible on the top of the base material of the new SiHy lens under ESEM. MPC surface gel was further confirmed by both AFM phase image and ESEM image of the new SiHy lens cross-section. AFM nanoindentation testing showed the new SiHy lens surface was approximately 5 times softer than the surface of comfilcon A, senofilcon A, and senofilcon C lenses (~400nm vs. ~80nm of indentation depth under the eyelid contact pressure). The coefficient of friction of the new SiHy lens was also at least 5 times lower than that of comfilcon A, senofilcon A, and senofilcon C lenses.
Conclusions :
A novel biomimetic MPC surface-modified SiHy contact lens was characterized for its surface structure and surface properties. The results indicate that the new SiHy lens has the exceptional characteristics of super-hydrophilicity, ultra-softness, and superior lubricity, which may enhance tear film stability and provide mechanical properties similar to ocular tissue, and is expected to achieve outstanding on-eye performance.
This is a 2021 ARVO Annual Meeting abstract.