Assessing the impact of lysozyme adsorption on the friction coefficient in Etafilcon A and Senofilcon A contact lenses

When a contact lens (CL) is placed in the eye, tear components begin to interact and accumulate on the lens surface. A commonly accumulated tear film protein on hydrogel CLs is lysozyme. The adsorption of proteins onto the CL can lead to discomfort, red eyes, or even inflammatory reactions. Notably, the friction coefficient of the CL has also been linked to similar symptoms. Nonetheless, few studies have explored the impact of tear protein deposition on the friction coefficient of CLs. In this context, the friction coefficient of the hydrogel CL Etafilcon A was investigated after incubation in solutions containing physiological concentrations of lysozyme. The following measurements were conducted under conditions of reduced dehydration to closely simulate actual wear conditions, aiming to mimic a 6 hour wear period. Before measuring friction, lysozyme adsorption was quantified using spectrophotometric assays. The findings indicate significant protein deposition on the CLs, while only minor changes in the friction coefficient were observed.