Hall B, et al. - This study is performed to compare and critically assess a variety of techniques to measure the quantity and biological activity of protein sorption to contact lenses over short time periods. The outcome of this study suggests that there are a wide variety of techniques to measure both the amount of protein and the biological activity of protein sorbed to soft contact lens materials. To measure the mass of protein sorbed to soft contact lenses (not just thin films) over short time periods, the method of choice must be I125 radiolabeling. This technique is sensitive enough to measure small amounts of deposited protein, provided steps are taken to limit and measure any interaction of the iodine tracer with the materials. To measure the protein activity over short time periods, the method of choice ought to be to quantify the biological function of sorbed proteins. This may require new methods or adaptations of existing ones.