Quantitative analysis of tear protein profile for soft contact lenses--a clinical study

Approximately 3% of the patients with refractive errors wear contact lenses. Recent studies revealed contradictory results regarding the changes of the tear film in contact lens wearers. The aim of this study was to analyze the influence of wearing contact lenses on the tear protein patterns. The study was performed using a new method to analyze quantitatively the tear proteins based on digital image analysis of electrophoretical separations followed by multivariate statistical calculations. Two groups were examined: 121 healthy volunteers (KO) and 66 wearers of soft contact lenses (KL). The tear proteins were separated by sodium dodecylsulfate polyacrylamide gel electrophoresis (SDS-PAGE). For each electrophoretic lane, a densitograph was built by digital image analysis. Subsequently a multivariate analysis of discriminance was performed. The concentration of the tear proteins lactoferrin, sIgA, lysozyme and albumin was slightly reduced. In contrast, the concentration of lipocalin was increased in the tears of contact lens wearers (p < 0.07). However, including all peaks found in each electrophoretic lane, the analysis of discriminance found a statistical significant difference between KO and KL (Wilks' Lambda = 0.88; p < 0.0001). Wearing contact lenses leads to significant changes in the composition of tear-film proteins. However, the pathomechanism of this alteration of the tear film is still unclear. Because of the large number of contact lens wearers, these alterations should be examined further.