Collection and concentration of tear proteins studied by SDS gel electrophoresis. Presentation of a new method with special reference to dry eye patients.

An obvious obstacle in the analysis of tear film samples from patients with dry eyes is the drastically reduced tear volume. To overcome this problem we have developed a method by which the surface of the eye is flushed with saline, diluting the sparse tear fluid, followed by a concentration of the wash fluid. We compared undiluted tears, diluted tears, tear fluid collected by flushing, reconcentrated diluted tears and reconcentrated flush fluid. Gel electrophoresis of the tear samples obtained showed a representative collection of tear proteins, with bands ranging in molecular weight from about 10 kDa to about 90 kDa. The method may therefore provide a useful alternative to the analysis of undiluted tear fluid in such patients. After storage at -80 degrees C for 1 month, electrophoresis often showed some weakening of band intensities. However, no specific loss of bands was found, and by ultracentrifugation a band profile similar to that of fresh, undiluted tears was obtained. For most purposes, therefore, samples may be kept by this means for later analysis.