UV-visible transmittance of silicone-hydrogel contact lenses measured with a fiber optic spectrometer

Abstract

Protein deposition is one of the most frequent contaminants occurring on hydrophilic contact lenses and may modify the lens optical properties. The silicone-hydrogel contact lenses usually adsorb a lower amount of proteins than the conventional hydrogel ones. However it is important to study the influence of protein deposits on some silicone-hydrogel contact lenses properties, such as UV-Visible transmittance. In this study it is measured de UV-Visible properties of new and worn silicone-hydrogel contact lenses and the transmittance changes that can occur with wear are quantified. An optical fiber spectrometer has been used for measuring the transmittance of contact lenses. This spectrometer has the advantage that the lens can be positioned horizontally and the light beam passes through it perpendicularly. For the measurements, it was necessary to make a special cuvette to put inside the lens and keep it submerged in sterile saline solution. The contact lenses used were Biofinity®. They are manufactured by CooperVision with a material whose technical name is Comfilcon A. This material has not yet been analyzed for this purpose. Moreover, in this type of studies are commonly taken lenses of power -3.00D, however we have not limited to a single power value but we have extended the range to lower and higher values regarding to the standard power in order to see how this parameter affects.