Purpose. Following the solubilization of protein from patient worn soft contact lenses and subsequent analysis via SDS-PAGE, an unidentified 30 kDa protein deposit was commonly observed. The mysterious deposit was found to accumulate on a variety of soft contact lens material.Methods. Acuvue®, Cibasoft®, Excelens®and Newvue®soft contact lenses were worn by three asymptomatic patients using both daily-wear and extended wear regimens. To characterize the unknown deposit, human tear samples and lens eluted protein were subjected to SDS-PAGE, immunoblotting, enzymatic assays and protein sequencing.Results. Results show that the 30 kDa protein deposit is the homologous dimer of tear lysozyme. Polymerized lysozyme was found on each of the three lens materials within one h of wear. However, the dimer was not present in the normal tear film.Conclusions. Therefore, this dimerization phenomenon is the result of an aggregation and interaction of lysozyme with various soft contact lens polymers.