(710g) Simulation of Lysozyme Concentration Profiles at Contact Lenses and Effect of Homogenous Diffusion Coefficient

Contact lenses have a wide usage in biomedical applications. Lifetime of contact lenses depend on their oxygen permeability and the accumulation of the teardrops components, e.g. proteins, lipids. Especially the proteins adsorbed on the contact lenses may increase the vision defects and risk for serious eye-disorders. Therefore, the information on the amount and conditions of the accumulation of proteins in teardrops is important.

In the present study, the concentration profiles of lysozyme -the protein having the highest concentration in teardrops- in a contact lens during its adsorption and desorption was investigated. The simulation of the protein accumulation was carried out using a new method based on general rate model approach. According to the model, concentration of lysozyme in the bulk liquid phase; liquid and solid concentrations at the interface; and solid phase concentration were individually defined and the equilibrium between these concentrations were described according to the circumstances. The algorithms needed for the concentration profiles on the derived mathematical expressions have been prepared within the study.

In experimental studies, Etafilcon A (Johnson&Johnson) contact lenses were used. Lysozyme was dissolved in phosphate buffered saline (PBS) solution to simulate the human teardrop for the adsorption of the protein on the lenses. In desorption studies, protein-free PBS solution was used as the cleaning solution and the accumulation of lysozyme was observed. Using the proposed model, the information on the period the lenses can be used during the day and that needs to be kept in the cleaning solution were obtained. Additionally, the model enables the calculation of the homogenous diffusion coefficient of lysozyme in the contact lens.