Investigation on the solid diffusivities and concentration profiles of proteins in contact lenses

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. They may increase the vision defects and cause eye-diseases. Therefore, the information about the usage time and the cleaning procedure of the contact lenses has a great importance. In this MS thesis, the concentration profiles of lysozym, which has the highest concentration among the proteins in teardrops, during its adsorption and desorption. The general rate model based characteristic edge length method which describes the protein transport mechanism to the contact lenses has been developed. According to this, concentrations in the bulk liquid phase, at the liquid and solid interphase and in the solid phase was individually defined and the equilibrium conditions between these were determined. Experiments were carried out by using the lysozyme as teardrop protein and the PBS buffer solution as medium solution and the Etafilcon A Acuvue 2 brand contact lenses as adsorbent. The algorithm required for the solution of mathematical expressions was prepared within the thesis. Consequently, homogeneous diffusion coefficient (Ds) was found as 1.730x10-8 cm2/s. In addition, it was found that when the Etafilcon A contact lenses were utilized for 6 h, 2 h was enough for their cleaning in PBS. In summary in this MS thesis, information about the usage time of contact lenses and the period to be kept in cleaning solution during the day time was determined. The diffusion coefficient and concentration profiles of lysozyme were obtained by experimental and theoretical studies.